Capture cross-section and density of deep gap states in a−SiHx schottky barrier structures

Recombination of charge carriers in a?SiH_x Schottky barriers with density of states near mid-gap ranging from 2.8×10¹⁵?7×10¹⁶cm^-1eV^-1 is attributed to recombination centers with hole capture cross-section of 1.3×10^-15cm².     

Thin TiO2 grown by metal–organic chemical vapor deposition on (NH4)2S x -treated InP

The electrical characteristics of thin TiO₂ films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO₂ film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10⁻² and 1.1×10⁻⁴ A/cm² at +2 V bias and 1.6×10⁻¹ and 8.3×10⁻⁴ A/cm² at −2 V bias. The lower leakage currents of TiO₂ with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide charge number density are 33 and 2.5×10¹³ cm², respectively. The lowest mid-gap interface state density is around 7.6×10¹¹ cm⁻² eV⁻¹. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm.     

Silicon negative ion implantation induced vacancy defects in thermally grown SiO2 thin films

ABSTRACT

Thermally grown SiO₂ thin films on a silicon substrate implanted with 100?keV silicon negative ions with fluences varying from 1?×?10¹⁵ to 2?×?10¹⁷ ions cm^?2 have been investigated using Electron spin resonance, Fourier transforms infrared and Photoluminescence techniques. ESR studies revealed the presence of non-bridging oxygen hole centers, E′-centers and P_b-centers at g-values 2.0087, 2.0052 and 2.0010, respectively. These vacancy defects were found to increase with respect to ion fluence. FTIR spectra showed rocking vibration mode, stretching mode, bending vibration mode, and asymmetrical stretching absorption bands at 460, 614, 800 and 1080?cm^?1, respectively. The concentrations of Si–O and Si–Si bonds estimated from the absorption spectra were found to vary between 11.95?×?10²¹ cm^?3 and 5.20?×?10²¹ cm^?3 and between 5.90?×?10²¹ cm^?3 and 3.90?×?10²¹ cm^?3, respectively with an increase in the ion fluence. PL studies revealed the presence of vacancies related to non-bridging oxygen hole centers, which caused the light emission at a wavelength of 720?nm.     

Diffusion studies of Be-implanted GaAs by SIMS and electrical profiling

Secondary ion mass spectrometry (SIMS) has been used with differential resistivity and Hall effect measurements to study the 900°C diffusion of implanted Be in GaAs. Some outdiffusion of Be into the Si₃N₄ encapsulant occurs for surface Be concentrations above 1 × 10¹⁸cm^?3. However, excellent agreement between the electrical and atomic profiles indicates that 85–100% of the Be remaining after annealing is electrically active. The concentration-dependent diffusion observed for implanted Be in GaAs was not significantly altered in experiments using hot substrate implants, two-step anneals, or annealing with Ga and As overpressure.     

Characterization of SiON/InP MOS structure with sulfidation, fluorination, and hydrogenation

Liquid phase deposited SiON film on InP with (NH₄)₂S treatment shows superior electrical characteristics due to the reduction of native oxides and sulfur passivation. Simultaneously, HF in SiON liquid phase deposition solution can effectively reduce residual native oxides on InP and provide fluorine passivation in SiON/InP film and interface. With post-metallization annealing (PMA), hydrogen ions can further passivate defects in SiON/InP film and interface. With these treatments, the PMA-LPD-SiON/(NH₄)₂S-treated InP MOS structure shows excellent electrical characteristics. With the physical thickness of 5.4 nm, the leakage current densities can be as low as 1.25×10^?7 and 6.24×10^?7 A/cm² at ±2 V, and the interface state density is 3.25×10¹¹ cm^?2?eV^?1.     

Effects of silicon negative ion implantation in semi-insulating gallium arsenide

ABSTRACT

In the present work, effects of silicon negative ion implantation into semi-insulating gallium arsenide (GaAs) samples with fluences varying between 1?×?10¹⁵ and 4?×?10¹⁷?ions?cm^?2 at 100?keV have been described. Atomic force microscopic images obtained from samples implanted with fluence up to 1?×?10¹⁷?ion?cm^?2 showed the formation of GaAs clusters on the surface of the sample. The shape, size and density of these clusters were found to depend on ion fluence. Whereas sample implanted at higher fluence of 4?×?10¹⁷?ions?cm^?2 showed bump of arbitrary shapes due to cumulative effect of multiple silicon ion impact with GaAs on the same place. GXRD study revealed formation of silicon crystallites in the gallium arsenide sample after implantation. The silicon crystallite size estimated from the full width at half maxima of silicon (111) XRD peak using Debye-Scherrer formula was found to vary between 1.72 and 1.87?nm with respect to ion fluence. Hall measurement revealed the formation of n-type layer in gallium arsenide samples. The current–voltage measurement of the sample implanted with different fluences exhibited the diode like behavior.     

Effect of series resistance on the performance of silicon Schottky diode in the presence of tin oxide layer

The current–voltage (I–V) characteristics of Al/SnO₂/p-Si (MIS) Schottky diodes prepared by means of spray deposition method have been measured at 80, 295 and 350 K. In order to interpret the experimentally observed non-ideal Al/SnO₂/p-Si Schottky diode parameters such as, the series resistance R_s, barrier height Φ_B and ideality factor n, a novel calculation method has been reported by taking into account the applied voltage drop across interfacial oxide layer V_i and ideality factor n in the current transport mechanism. The values obtained for V_i were subtracted from the applied voltage values V and then the values of R_s were recalculated. The parameters obtained by accounting for the voltage drop V_i have been compared with those obtained without considering the above voltage drop. It is shown that the values of R_s estimated from Cheung’s method were strongly temperature-dependent and decreased with increasing temperature. It is shown that the voltage drop across the interfacial layer will increase the ideality factor and the voltage dependence of the I–V characteristics. The interface state density N_ss of the diodes has an exponential growth with bias towards the top of the valance band for each temperature; for example, from 2.37 × 10¹³ eV⁻¹ cm⁻² in 0.70−E_v eV to 7.47 × 10¹³ eV⁻¹ cm⁻² in 0.62−E_v eV for 295 K. The mean N_ss estimated from the I–V measurements decreased with increasing the temperature from 8.29 × 10¹³ to 2.20 × 10¹³ eV⁻¹ cm⁻².     

Formation of bubbles and blisters in hydrogen ion implanted polycrystalline tungsten

ABSTRACT

Tungsten (W) has been regarded as one of the most promising plasma facing materials (PFMs) in fusion reactors. The formation of bubbles and blisters during hydrogen (H) irradiation will affect the properties of W. The dependence of implantation conditions, such as fluence and energy, is therefore of great interest. In this work, polycrystalline tungsten samples were separated into two groups for study. The thick samples were implanted by 18?keV H₃⁺ ions to fluences of 1?×?10¹⁸, 1?×?10¹⁹ and 1?×?10²⁰ H⁺/cm², respectively. Another thick sample was also implanted by 80?keV H₂⁺ ions to a fluence of 2?×?10¹⁷ H⁺/cm² for comparison. Moreover, the thin samples were implanted by 18?keV H₃⁺ ions to fluences of 9.38?×?10¹⁶, 1.88?×?10¹⁷ and 5.63?×?10¹⁷ H⁺/cm², respectively. Focused ion beam (FIB) combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for micro-structure analysis, while time-of-flight ion mass spectrometry (ToF-SIMS) was used to characterize the H depth profile. It is indicated that bubbles and blisters could form successively with increasing H⁺ fluence. H bubbles are formed at a fluence of ～5.63?×?10¹⁷ H⁺/cm², and H blisters are formed at ～1?×?10¹⁹ H⁺/cm² for 18?keV H₃⁺ implantation. On the other hand, 80?keV H₂⁺ ions can create more trapping sites in a shallow projected range, and thus enhancing the blisters formation with a relatively lower fluence of 2?×?10^17?H⁺/cm². The crack-like microstructures beneath the blisters are also observed and prefer to form on the deep side of the implanted range.     

离子注入形成SOI结构的界面及埋层的俄歇能谱研究

本文中研究了O⁺(200keV,1.8×10¹⁸/cm²)和N⁺(190keV,1.8×10¹⁸/cm²)注入Si形成SOI(Silicon on Insulator)结构的界面及埋层的化学组成。俄歇能谱的测量和研究结果表明:注O⁺的SOI结构在经1300℃,5h退火后,其表层Si和氧化硅埋层的界面存在一个不饱和氧化硅状态,氧化硅埋层是由SiO₂相和这不饱和氧化硅态组成,而且氧化硅埋层和体硅界面不同于表层Si和氧化硅埋层界面;注N⁺的SOI结构在经1200℃,2h退火后,其氮化硅埋层中存在一个富N的疏松夹层,表层Si和氮化硅埋层界面与氮化硅埋层和体硅界面性质亦不同。这些结果与红外吸收和透射电子显微镜及离子背散射谱的分析结果相一致。还对两种SOI结构界面与埋层的不同特征的原因进行了分析讨论。 关键词：     

Analysis of current–voltage and capacitance–voltage characteristics of perylene-monoimide/n-Si Schottky contacts

The electrical and interface state properties of Au/perylene-monoimide (PMI)/n-Si Schottky barrier diode have been investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements at room temperature. A good rectifying behavior was seen from the I–V characteristics. The series resistance (R_s) values were determined from I–V and C–V characteristics and were found to be 160 Ω and 53 Ω, respectively. The barrier height (Φ_b) of Au/PMI/n-Si Schottky diode was found to be 0.694 eV (I–V) and 0.826 eV (C–V). The ideality factor (n) was obtained to be 4.27 from the forward bias I–V characteristics. The energy distribution of interface state density (N_ss) of the PMI-based structure was determined, and the energy values of N_ss were found in the range from E_c ? 0.508 eV to E_c ? 0.569 eV with the exponential growth from midgap toward the bottom of the conduction band. The values of the N_ss without R_s are 2.11 × 10¹² eV^?1 cm^?2 at E_c ? 0.508 eV and 2.00 × 10¹² eV^?1 cm^?2 at E_c ? 0.569 eV. Based on the above results, it is clear that modification of the interfacial potential barrier for metal/n-Si structures has been achieved using a thin interlayer of the perylene-monomide.     

Photoluminescent studies of the condensed phase in phosphorus-doped silicon

Photoluminescent studies give evidence for the existence of the electron—hole droplet in phosphorus-doped silicon in the impurity concentration range 9.0 × 10¹⁵cm^?3 ? N_D ? 4.3 × 10¹⁹cm^?3.     

Study of hydrogenated AlN as an anti‐reflective coating and for the effective surface passivation of silicon

Stacks of aluminum oxide and silicon nitride are frequently used in silicon photovoltaics. In this Letter, we demonstrate that hydrogenated aluminum nitride can be an alternative to this dual‐layer stack. Deposited on 1 Ω cm p‐type FZ silicon, very low effective surface recombination velocities of 8 cm/s could be reached after firing at 820 °C. This excellent passivation is traced back to a high density of fixed charges at the interface of approximately –1 × 10¹² cm^–2 and a very low interface defect density below 5 × 10¹⁰ eV^–1 cm^–2. Furthermore, spectral ellipsometry measurements reveal that these aluminum nitride layers have ideal optical properties for use as anti‐reflective coatings. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Deep levels in gallium arsenide by capacitance methods

The three capacitance methods, i.e., TSCAP, PHCAP, and transient capacitance measurements, are applied to determine electronic properties of deep levels inn-GaAs. In the boat-grown wafer detected are the 0.30 eV electron trap withN _T =3.6×10¹⁶ cm^?3 andS _n =2.4×10^?15 cm², and the 0.75 eV electron trap withN _T =2.0×10¹⁶ cm^?3 andS _n =1.2×10^?14 cm². In the epitaxial wafer, the 0.45 eV hole trap is detected withN _T >1.5×10¹³ cm^?3 andS _p =1.4×10^?14 cm² as well as the 0.75 eV electron trap withN _T =2.4×10¹³ cm^?3.     

Evaporated a-Si films with low ESR defect density by hydrogenation under NH3 ambient

a-Si films were obtained by a reactive evaporation of Si atoms with an electron gun, under a NH₃ ambient of 5 × 10^?5 torr. The H introduced amount efficiently reduces the ESR dangling bond density from 4 × 10¹⁹ cm^?3 in pure samples to 2 × 10¹⁷ cm^?3. The hydrogen presence is evidence by both the Si-H infrared bands and the strong spin-density increase with annealing. This increase, beginning at a temperature of 350°C, is attributed to the H effusion. XPS measurements show also an incorporation of bonded nitrogen.     

Improved electrical properties of HfTiO/GeO x N y gate dielectric Ge MOS capacitors by using wet–NO Ge-surface pretreatment

Reactive cosputtering is employed to prepare high-permittivity HfTiO gate dielectric on n-Ge substrate. Effects of Ge-surface pretreatment on the interface and gate leakage properties of the dielectric are investigated. Excellent performances of Al/HfTiO/GeO _x N _y /n-Ge MOS capacitor with wet–NO surface pretreatment have been achieved with a interface-state density of 2.1×10¹¹ eV⁻¹ cm⁻², equivalent oxide charge of −7.67×10¹¹ cm⁻² and gate leakage current density of 4.97×10⁻⁵ A/cm² at V _g =1 V.     

Damage and lattice location studies in Hg implanted Hg1–xCdxTe

Abstract

Rutherford backscattering (RBS) and ion induced X-ray (PIXE) channeling experiments have been used to study the damage accompanying Hg and Al implantations into Hg_0.8Cd_0.2 Te and its annealing as well as to determine the location of Hg in the crystal.

The damage induced by the implantation of 300 keV Hg and 250 keV Al ions at room temperature was found from RBS channeling studies to reach a saturation level at doses of 1 × 10¹⁴ cm^?2 and 3 × 10¹⁴ cm^?2 respectively. The damage resembles that characteristic for extended defects and it anneals at ≈ 300°C.

The location of the constituents of Hg implanted Hg_0.8 Cd_0.2 Te was studied by PIXE channeling observing the characteristic X-rays for each element. Angular scans indicate that the channels are mostly blocked by Hg atoms for both unannealed and, to a lesser extent, annealed crystals. This observation supports the suggestion that interstitial Hg atoms may be responsible for the conductivity of Hg implanted Hg_1–x Cd_g Te.     

Conduction through localized states in a single crystal of the TlGa<Subscript>0.5</Subscript>Fe<Subscript>0.5</Subscript>Se<Subscript>2</Subscript> alloy

Layered single crystals of the TlGa_0.5Fe_0.5Se₂ alloy in a dc electric field at temperatures ranging from 128 to 178 K are found to possess variable-range-hopping conduction along natural crystal layers through states localized in the vicinity of the Fermi level. The parameters characterizing the electrical conduction in the TlGa_0.5Fe_0.5Se₂ crystals are estimated as follows: the density of states near the Fermi level N_F = 2.8 × 10¹⁷ eV^?1 cm^?3, the spread in energy of these states ΔE = 0.13 eV, the average hopping length R_av = 233 Å, and the concentration of deep-lying traps N _t = 3.6 × 10¹⁶ cm^?3.     

控制氧化层对双势垒纳米硅浮栅存储结构性能的影响

在等离子体增强化学气相沉积(PECVD)系统中,利用逐层淀积非晶硅(a-Si)和等离子体氧化相结合的方法制备二氧化硅(SiO₂)介质层.电容电压(C-V)和电导电压(G-V)测量结果表明：利用该方法在低温(250 ℃)条件下制备的SiO₂介质层均匀致密,其固定氧化物电荷和界面态密度分别为9×10¹¹cm^-2和2×10¹¹cm^-2·eV^-1,击穿场强达4.6 MV/cm,与热氧化形成的SiO₂介质层的性质相当.将该SiO₂介质层作为控制氧化层应用在双势垒纳米硅(nc-Si)浮栅存储结构中,通过调节控制氧化层的厚度,有效阻止栅电极与nc-Si之间的电荷交换,延长存储时间,使存储性能得到明显改善. 关键词： 等离子体氧化 二氧化硅 纳米硅 控制氧化层     

The thermal stability of atomic layer deposited HfLaOx: Material and electrical characterization

HfLaO_x based Metal–oxide–semiconductor capacitors were fabricated by atomic layer deposition in this work. The material and electrical properties of the films along with the high temperature thermal treatment were investigated. It was found that samples undergoing annealing at 900 °C exhibited the best performance. The film was found to be crystallized to a cubic structure at 900 °C, and the roughness of the films was estimated to be 0.332 nm. For electrical characterization, the C–V curve of the film is in good agreement with the corresponding simulated curve, and the capacitor does not show any hysteresis. Moreover, the D_it near the center of silicon band gap exhibits lowest value, and it was calculated to be 2.28 × 10¹¹ eV^?1 cm^?2.     

Hopping conductivity of carbynes modified under high pressures and temperatures: Galvanomagnetic and thermoelectric properties

The conductivity, thermopower, and magnetoresistance of carbynes structurally modified by heating under a high pressure are investigated in the temperature range 1.8–300 K in a magnetic field up to 70 kOe. It is shown that an increase in the synthesis temperature under pressure leads to a transition from 1D hopping conductivity to 2D and then to 3D hopping conductivity. An analysis of transport data at T ≤ 40 K makes it possible to determine the localization radius a ～ (56?140) Å of the wave function and to estimate the density of localized states _g(E _F) for various dimensions d of space: _g(E _F) ≈ 5.8 × 10⁷ eV^?1 cm^?1 (d=1), _g(E _F) ≈5×10¹⁴ eV^?1 cm ^?2 (d=2), and _g(E _F)≈1.1×10²¹ eV^?1 cm_?3 (d=3). A model for hopping conductivity and structure of carbynes is proposed on the basis of clusterization of sp ² bonds in the carbyne matrix on the nanometer scale.