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1.
+ silicon wafer held at 573 K, are measured over a temperature range 37–307 K and analyzed in terms of thermionic emission–diffusion
(TED) theory by incorporating the concept of barrier inhomogeneities through a Gaussian distribution function. The process
adopted is shown to yield an ideal Schottky diode with a near constant barrier height of 0.734 V and ideality factor 1.05
in the temperature interval 215–307 K. Below 215 K, both the barrier height (φbo) and the ideality factor (η) exhibit abnormal temperature dependence and are explained by invoking two sets of Gaussian distributions
of barrier heights at 84–215 K and 37–84 K. Further, it is demonstrated that the forward bias makes the Gaussian distribution
dynamic so that the mean fluctuates (i.e., increases or decreases depending on whether its voltage coefficient is positive
or negative) and the standard deviation decreases progressively, i.e., the barrier homogenizes temporarily. The changes occur
in such a way that the apparent barrier height at any bias is always higher than at zero-bias. Finally, it is pointed out
that the presence of single/multiple distributions can be ascertained and the values of respective parameters deduced from
the φap vs. 1/T plot itself. Also, the inverse ideality factor versus inverse temperature plot provides bias coefficients of the
mean barrier height and standard deviation of the distribution function.
Received: 6 January 1997/Accepted: 29 April 1997 相似文献
2.
Pt-Ir silicide Schottky diodes were formed by e-beam evaporation of Pt and Ir onto p-Si(100) substrates in high vacuum with
subsequent RTA-annealing at temperatures in the range of 300 to 500 °C. Rutherford Backscattering Spectrometry (RBS) and infrared
photoresponse (PR) measurements were performed to determine the composition and the infrared electrooptical properties of
the resulting films. Coevaporated Pt-Ir films are demixed during silicidation and form a PtSi layer at the interface to the
silicon substrate. The Schottky barrier height is that of a pure PtSi film. Ir deposited prior to Pt exhibits Pt diffusion
through the Ir layer. Only when the Ir film is reacted to IrSi by in situ annealing prior to Pt deposition, a mixed Ir-Pt
silicide Schottky barrier is obtained. Infrared photoemission then yields intermediate Schottky barrier heights between those
of PtSi and IrSi. From a detailed analysis of the photoemission characteristics, it is concluded that the intermediate barrier
height is due to an area average of PtSi and IrSi grains which coexist at the Si interface.
Received: 29 May 1996/Accepted: 12 August 1996 相似文献
3.
G. A. Adegboyega A. Poggi E. Susi A. Castaldini A. Cavallini 《Applied Physics A: Materials Science & Processing》1989,48(4):391-395
A wet chemical etch preceding the usual cleaning process has been found to yield Schottky barriers of high values on p-type silicon. This procedure produces a passivated surface layer which has resulted in Al/0-Si Schottky diodes with barrier height of 0.75 eV and ideality factor of 1.15. Measurements have confirmed the presence of electrically active donor-like states in this surface layer. The origin of the donor states is explained in terms of the deactivation of the boron acceptor by the formation ofH
+
B
– pairs. 相似文献
4.
M. Wittmer 《Applied Physics A: Materials Science & Processing》1990,51(6):451-454
Small-area high-barrier Schottky diodes have a very high dynamic resistance. Consequently, special care is needed when measuring the current-voltage characteristic of such diodes. The reported observation of carrier recombination in the depletion layer of high-barrier IrSi/Si Schottky diodes at room temperature is shown to be due to instrumental loading of the diodes. Careful measurements show that carrier recombination is observed only below 200 K and is dependent on the dimension of the diode. 相似文献
5.
S. Hardikar M.K. Hudait P. Modak S.B. Krupanidhi N. Padha 《Applied Physics A: Materials Science & Processing》1999,68(1):49-55
0 effect, the zero-bias barrier height was found to exhibit two different trends in the temperature ranges of 77–160 K and
160–300 K. The variation in the flat-band barrier height with temperature was found to be -(4.7±0.2)×104 eVK-1, approximately equal to that of the energy band gap. The value of the Richardson constant, A**, was found to be 0.27 A cm-2K-2 after considering the temperature dependence of the barrier height. The estimated value of this constant suggested the possibility
of an interfacial oxide between the metal and the semiconductor. Investigations suggested the possibility of a thermionic
field-emission-dominated current transport with a higher characteristic energy than that predicted by the theory. The observed
variation in the zero-bias barrier height and the ideality factor could be explained in terms of barrier height inhomogenities
in the Schottky diode.
Received: 4 December 1997/Accepted: 28 July 1998 相似文献
6.
E. Kabushemeye R. L. Van Meirhaeghe W. H. Laflère F. Cardon 《Applied Physics A: Materials Science & Processing》1991,52(1):60-64
Magnetron-sputtered CoSi2 and TiSi2 Schottky barriers on n- and p-type GaP were investigated. Their hitherto unknown barrier heights were determined to be 0.98 eV (for CoSi2/n-GaP and CoSi2/p-GaP), 0.91 eV (for TiSi2/n-GaP), and 0.90 eV (for TiSi2/p-GaP). It was found that magnetron-sputtering induced a compensated layer near the surface, both for n- and p-type GaP, with a thickness of about 0.05 m. As the dependence of the shift of the Mott-Schottky intercept with the V-axis on the substrate dopant concentration obeyed some specific law, we proposed that the defects are neutral complexes of dopant ions and sputter-induced native defects. These native defects were assumed to depend on the Fermi level position, namely the PGa antisite and the VP vacancy for p-GaP and the VGa vacancy for n-GaP. The conversion between these defects occurs by nearest neighbour hopping of a phosphorus atom. The Schottky barrier heights obtained on p-GaP could be explained by Fermi level pinning at the surface due to the PGa defects. This could not be confirmed by n-GaP as the energy level position of the VGa was not available. The defects could be annealed out between 200° C and 300° C and the associated change of the Schottky barrier height corroborated the proposed model.On leave from the Université de Burundi, Faculté des Sciences, Bujumbura, Burundi 相似文献
7.
R. Turan B. Aslan O. Nur M.Y.A. Yousif M. Willander 《Applied Physics A: Materials Science & Processing》2001,72(5):587-593
We have studied the effect of the strain relaxation on the band-edge alignments in a Pt/p-Si1-xGex Schottky junction with x=0.14 by internal photoemission spectroscopy and current–voltage measurements. We have shown that
the variations in the band-edge alignments can be observed directly by measuring the optical and electrical properties of
a simple Schottky junction. The strain in the Si1-xGex layer has been partially relaxed by thermal treatments at two different temperatures. The degree of relaxation and other
structural changes have been determined by a high-resolution X-ray diffractometer. Both optical and electrical techniques
have shown that the barrier height of the Pt/Si0.86Ge0.14 junction increases with the amount of relaxation in the Si1-xGex layer. This shows that the valence-band edge of the Si1-xGex layer moves away from the Fermi level of the Pt/Si1-xGex junction. The band-edge movement results from the increase in the band gap of the Si1-xGex layer after the strain relaxation. This result agrees with the theoretical predictions for the strain-induced effects on
the Si1-xGex band structure.
Received: 18 October 2000 / Accepted: 19 December 2000 / Published online: 23 March 2001 相似文献
8.
The results obtained in our previous work [4] are revised taking into account the dependence of the electron affinity on the polytype of silicon carbide SiC. The dependence of the energy level of vacancies in a polytype of silicon carbide on the band gap is determined from the data on the Schottky barrier height and is explained in the framework of a simple two-band model. 相似文献
9.
Keiji Maeda 《Applied Surface Science》2006,252(16):5659-5675
A mechanism of local lowering of the Schottky barrier height (SBH) is proposed, which causes nonideality in nearly ideal Au/n-Si and Au/n-GaAs Schottky barriers. Positively ionized defects generated by the process very close to the interface induce electrons in the metal-induced gap states (MIGS) and lower the SBH locally. The spatial density distribution of the ionized defects obtained from the SBH distribution is determined by the unique interaction with the MIGS. The defects are considered to have the negative-U property and are neutralized at very close positions to the MIGS. The potential distributions close to the interface have a considerable potential drop due to the large defect density. These inhomogeneous potentials are coincident with the energy level scheme of the defect identified as the defect causing the nonideality. This defect is Si self-interstitial in Au/Si SB, and As antisite in Au/n-GaAs SB. This MIGS with process-induced defect model supersedes the previously proposed two major Fermi level pinning models. The mystery of the T0 effect is solved. The thermionic-field emission current taking place in the strong electric field has influence on the I-V characteristics at low temperatures. Regarding the C-V characteristics of Au/Si SB, the observed extra capacitance under the forward bias is an experimental evidence in accordance with the proposed model. 相似文献
10.
The crystalline silicon thin-film solar cell combines, in principle, the advantages of crystalline silicon wafer-based solar
cells and of thin-film solar cell technologies. Its efficiency potential is the highest of all thin-film cells. In the “high-temperature
approach” thin silicon layers are deposited on substrates that withstand processing temperatures higher than 1000 °C. The
basic features of the high-temperature crystalline silicon thin-film cell technology are described and some important results
are discussed.
Received: 1 March 1999 / Accepted: 28 March 1999 / Published online: 24 June 1999 相似文献
11.
R. Steinke M. Hoffmann M. Böhmisch J. Eisenmenger K. Dransfeld P. Leiderer 《Applied Physics A: Materials Science & Processing》1996,64(1):19-27
We used a quartz tuning fork vibrating at 30 kHz both as an acoustic near field microscope and at the same time as a microscopic
Kelvin probe. One leg of the tuning fork carried a small gold electrode serving as a conducting vibrating tip. By using this
instrument and the method described here it is possible to measure simultaneously both the surface topography of the sample
surface and the contact potential between tip and sample. The topography is observed by operating the instrument as an acoustic
near field microscope. The contact potential between the vibrating tip and the sample gives rise to a displacement current
which is used here for the determination of the contact potential. In first applications of this method we demonstrate that
the contact potential can be measured with a sensitivity of at least 100 mV and a local resolution of about 5 μm. It seems
possible to use the microscopic method described here also for investigating local potentials at low temperatures and even
in high magnetic fields. For example, the microscopic study of the Hall voltages in the quantum Hall effect might be an interesting
application.
Received: 22 April 1996/Accepted: 18 June 1996 相似文献
12.
C. Tomas J.P. Girardeau-Montaut M. Afif M. Romand M. Charbonnier T.M. Duc 《Applied Physics A: Materials Science & Processing》1997,64(5):467-471
3+ :YAG laser with 5th harmonic generator, generating 16 ps duration pulses at 213 nm, with energies up to 0.5 mJ. Experimental results concerning
the action of laser pulses, as well as the effects of residual pressure on the cleanliness of the photocathodes surface are
presented and discussed. Influence of laser pulses and residual pressure on the work function of the metal are also investigated.
Received: 15 April 1996/Accepted: 5 November
1996 相似文献
13.
Mathias Mews Caspar Leendertz Michael Algasinger Svetoslav Koynov Lars Korte 《固体物理学:研究快报》2014,8(10):831-835
Excellent passivation of black silicon surfaces by thin amorphous silicon layers deposited with plasma enhanced chemical vapor deposition is demonstrated. Minority charge carrier lifetimes of 1.3 milliseconds, enabling an implied open‐circuit voltage of 714 mV, were achieved. The influence of amorphous silicon parasitic epitaxial growth and thickness, as well as of the texture depth is investigated. Furthermore, quantum efficiency gains for wavelengths above 600 nm, as compared to random textured solar cells, are demonstrated in 17.2% efficient amorphous–crystalline silicon heterojunction solar cells with black silicon texture. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
14.
J. Kudrna I. Pelant J. Štěpánek F. Trojánek P. Malý 《Applied Physics A: Materials Science & Processing》2002,74(2):253-256
We have studied ultra-fast carrier dynamics of photo-excited carriers in hydrogenated microcrystalline silicon prepared by
a very high frequency glow-discharge technique. We report on direct observation of two types of dynamics using selective photo-excitation
in picosecond pump and probe measurements. One type of the observed dynamics has been found to be independent of the sample
preparation, while the other reflects the relative weights of crystalline and amorphous fractions. We propose a simple rate-equation
model that describes the carrier dynamics in microcrystalline silicon in terms of the composition of those in Si microcrystallites
and in the a-Si:H tissue which surrounds the microcrystallites. The model without any fitting parameters reproduces the experimental
data very well when the dynamics are scaled with relative volume fractions as obtained from Raman spectra.
Received: 23 November 2000 / Accepted: 17 March 2001 / Published online: 23 May 2001 相似文献
15.
The forward bias current-voltage (I-V) characteristics of Al/p-Si (MS) Schottky diodes with native insulator layer were measured in the temperature range of 80-300 K. The obtained zero bias barrier height ΦB0(I-V), ideality factor (n) and series resistance (Rs) determined by using thermionic emission (TE) mechanism show strong temperature dependence. There is a linear correlation between the ΦB0(I-V) and n because of the inhomogeneties in the barrier heights (BHs). Calculated values from temperature dependent I-V data reveal an unusual behaviour such that the ΦB0 decreases, as the n and Rs values are increasing with decreasing absolute temperature, and these changes are more pronounced especially at low temperatures. Such temperature dependence of BH is contradictory with the reported negative temperature coefficient of the barrier height. In order to explain this behaviour we have reported a modification in the expression reverse saturation current Io including the n and the tunnelling factor (αΧ1/2δ) estimated to be 15.5. Therefore, corrected effective barrier height Φbef.(I-V) versus temperature has a negative temperature coefficients (α = −2.66 × 10−4 eV/K) and it is in good agreement with negative temperature coefficients (α = −4.73 × 10−4 eV/K) of Si band gap. In addition, the temperature dependent energy distribution of interface states density Nss profiles was obtained from the forward bias I-V measurements by taking into account the bias dependence of the Φe and n. The forward bias I-V characteristics confirm that the distribution of Nss, Rs and interfacial insulator layer are important parameters that the current conduction mechanism of MS Schottky diodes. 相似文献
16.
R.F. Schmitsdorf W. Mönch 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(3):457-466
Unreconstructed interfaces may be prepared by evaporation of thick Pb films onto surfaces at room temperature. Current-voltage and capacitance-voltage characteristics of such Schottky contacts were measured in the temperature range between 140 and 300 K. The experimental data are analyzed by applying
the thermionic-emission theory of inhomogeneous metal-semiconductor contacts as well as the “standard” thermionic-emission
theory. From both methods the Schottky barrier height of laterally homogeneous contacts results as 0.724 eV. This value is by 74 meV larger than the previously observed barrier heights of laterally homogeneous
interfaces. Similar differences were reported for unreconstructed and reconstructed Al- and contacts. The reduced barrier heights of all these interfaces are explained by the electric dipole associated with the stacking faults of reconstructions at surfaces and interfaces.
Received: 14 May 1998 /Revised and Accepted: 7 September 1998 相似文献
17.
L. Szaro J. Rębisz J. Misiewicz 《Applied Physics A: Materials Science & Processing》1999,69(4):409-413
Surface photovoltage spectra in semiconductors are analyzed when the sub-band-gap illumination induces the electron transitions
from surface states to the conduction band under the assumption that distribution of surface states is continuous. From analysis
performed it follows that the fictitious densities of surface states can be induced due to the wavelength dependence of the
photoionization capture cross-section of surface states for electrons and by the electron recombination capture cross-section
of surface states which depends on the energy position of surface states in the energy gap. The high illumination intensity
(laser illumination), which makes completely empty the surface states, can eliminate the fictious surface states when the
density of surface states is not very large, the temperature of measurements is low, and the surface potential barrier is
high.
Received: 24 June 1998 / Accepted: 29 March 1999 / Published online: 14 June 1999 相似文献
18.
Frequency differences of up to 900 GHz between two laser lines near 568 nm were measured by mixing laser light and harmonics of 90 GHz microwave radiation. The Schottky point contact diodes used consisted of tungsten tips onn-GaAs bases with different degrees of doping. The formation of the contacts and the sensitivity and frequency limitations of the device are discussed. 相似文献
19.
B. Bescós R. Hoch H.-J. Schmidtke G. Gerber 《Applied physics. B, Lasers and optics》2000,71(3):373-379
Femtosecond-laser spectroscopy is used to study the photoionization and photofragmentation of large neutral silicon clusters
in a beam. Silicon clusters Sin with sizes up to n≈6000, corresponding to nanoparticles with diameters up to 6 nm, are generated in a laser vaporization
source. Nanosecond- and femtosecond-laser ionization are employed to characterize the free silicon nanoparticles. Excitation
with intense femtosecond-laser pulses leads to prompt formation of doubly and triply charged Sin clusters. Additionally, strong fragmentation of charged clusters occurs by Coulomb explosion, resulting in high released
kinetic energies. Multiply charged atoms up to Si4+ with initial kinetic energies in the range of 500 eV are observed for laser intensities of about 1013 W/cm2. Pump–probe spectroscopy yields decay times of the intermediate resonances of the nanoparticles.
Received: 22 January 2000 / Published online: 7 August 2000 相似文献
20.
Potential of amorphous silicon for solar cells 总被引:1,自引:0,他引:1
This paper reviews recent developments in the field of amorphous-silicon-based thin-film solar cells and discusses potentials
for further improvements. Creative efforts in materials research, device physics, and process engineering have led to highly
efficient solar cells based on amorphous hydrogenated silicon. Sophisticated multijunction solar cell designs make use of
its unique material properties and strongly suppress light induced degradation. Texture-etching of sputtered ZnO:Al films
is presented as a novel technique to design optimized light trapping schemes for silicon thin-film solar cells in both p-i-n
and n-i-p device structure. Necessary efforts will be discussed to close the efficiency gap between the highest stabilized
efficiencies demonstrated on lab scale and efficiencies achieved in production. In case of a-Si:H/a-Si:H stacked cells prepared
on glass substrates, significant reduction of process-related losses and the development of superior TCO substrates on large
areas promise distinctly higher module efficiencies. A discussion of future perspectives comprises the potential of new deposition
techniques and concepts combining the advantages of amorphous and crystalline silicon thin-film solar cells.
Received: 1 March 1999 / Accepted: 28 March 1999 / Published online: 14 June 1999 相似文献