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1.
Carbon doping of GaAs with carbon tetrabromide (CBr4) in low pressure MOVPE has been investigated and applied to the fabrication of GaInP/GaAs HBTs. Especially the hydrogen incorporation and the associated acceptor passivation has been studied. The hydrogen found in single GaAs:C layers is predominantly incorporated during cooling the sample under AsH3 after growth, n-Type capping layers can block this H indiffusion and GaAs:C base layers in HBTs show much lower H concentrations than GaAs:C single layers without a cap. A further reduction of acceptor passivation is possible by optimization of the growth procedure. First HBTs processed from layers with a base that was doped using CBr4 show promising DC and HF performance (β = 45, for 2 × 20 μm2 devices).  相似文献   

2.
Hydrogen radicals are decisive for the low-temperature growth and carbon doping of In0.53Ga0.47As in LP-MOVPE. This is demonstrated for the growth of highly p-type doped In0.53Ga0.47As layers with CCl4 as dopant source. Perturbed angular correlation measurements (PAC) were used to investigate the passivation of acceptors by hydrogen in low-temperature grown In0.53Ga0.47As. Based on the above analysis an InP-based layer stack is developed which employs low-temperature growth of the base layer, high-temperature growth of the remaining HBT layers, and an in situ post-growth annealing under TMAs/N2 ambient.  相似文献   

3.
The suitability of an N2 carrier in LP-MOVPE of GaInAs/InP device structures and for the growth of (Al)GaInP is investigated for the first time. Al-free GaInAs/InP HEMTs and MSM photodetectors exhibit cutoff frequencies of ft = 135 GHz and fmax = 200 GHz and a bandwidth of 16 GHz and responsivity of 0.27 A/W, respectively. AlGaInP and GaInP layers deposited using the optimized growth conditions showed excellent structural, optical and homogeneity properties. For example X-ray diffractograms with FWHMs as low as 15–16 arcsec for 1 μm thick layers and 300 K photoluminescence mappings over full 2 inch wafers with standard deviations of ±0.23 and ±0.26 nm were obtained for both materials.  相似文献   

4.
Heavily magnesium-doped p-type-InGaAs layers on InP(100) substrates were successfully grown, for the first time, by low-pressure metalorganic chemical vapor deposition (MOCVD) using bis-ethylcyclopentadienyl-magnesium, (C2H5C5H4)2Mg (EtCp2Mg), as organometallic precursor for the Mg. It was experimentally verified that the room-temperature hole concentration of Mg into InGaAs increased with increase of the V/III ratio and decrease of the growth temperature. A maximum hole concentration of over 4 × 1019 cm−3 was obtained. The diffusion coefficient of Mg in InGaAs was experimentally derived to be 10−12 cm2/s at 800°C, which was comparable to that of Be. Finally, InP/InGaAs heterojunction bipolar transistors (HBTs) with Mg-doped bases were fabricated successfully. Measured maximum current gain was about 320 with a 90 nm thick base and a sheet resistance of the base layer of 1.28 kΩ/sq.  相似文献   

5.
The conditions under which selective epitaxial growth (SEG) is achieved in UHV-CVD with Si2H6 are determined by the amount of Si2H6 molecules being supplied, and there is a critical gas supply amount (Fc) beyond which SEG will break down and lose its selectivity. The value of Fc is itself determined by two factors, growth temperature and the material used for masking, i.e. SiO2, Si3N4. We found that this limiting factor of Fc was increased through the addition of a small amount of Cl2, and that after such addition, the resulting decrease in growth rate is minimal.  相似文献   

6.
The growth of Si(001) from a gas source molecular beam epitaxy system (Si-GSMBE) using disilane (Si2H6) was investigated using reflection high-energy electron diffraction (RHEED). The surface reconstructions occurring between 100 and 775°C were studied as a function of both substrate temperature and surface coverage. We report the first observation of (2x2) and c(4x4) reconstructions during growth at substrate temperatures near 645°C using Si2H6. All growth was found to be initiated by the formation of three-dimensional (3D) islands which coalesced at substrate temperatures above 600°C. The surface reconstruction was found to change from a disordered to an ordered (2x1)+(1x2) structure at 775°C via intermediate (2x2) and c(4x4) phases. Thereafter, growth was found to proceed in a 2D layer-by-layer fashion, as evidenced by the observation of RHEED intensity oscillations. This technique has been used, for the first time, to calibrate growth rates during Si-GSMBE. The intensity oscillations were measured as a function of both substrate temperature and incident beam flux. Strong and damped oscillations were observed between 610 and 680°C, in the two-dimensional growth regime. At higher temperatures, growth by step propagation dominated while at lower temperatures, growth became increasingly three-dimensional and consequently oscillations were weak or absent. Similarly, there was a minimum flux limit ( <0.16 SCCM), below which no oscillations were recorded.  相似文献   

7.
ZnSe was grown on GaAs(100) substrates by photoassisted MOVPE using the precursors dimethylzinc-triethylamine (DMZn-TEN) and ditertiarybutylselenide (DtBSe). The optimal growth temperature was Tg = 300°C. Above 300°C no enhancement of growth rate was observed under illumination. Furthermore, nitrogen doping experiments were performed using phenylhydrazine, allylamine and tert-butylamine as nitrogen precursors. Nitrogen concentrations up to 1019 cm−3 (SIMS) were achieved with input flow ratios as low as [PhHz]/[Se] = 4 × 10−4. All as-grown samples were highly compensated. Successful nitrogen incorporation was also observed with allylamine. However, the use of tert-butylamine together with the adduct compound DMZn-TEN showed no incorporation of nitrogen.  相似文献   

8.
Highly p-type carbon-doped GaAs epitaxial layers were obtained using diiodomethane (CI2H2) as a carbon source. In the low 1019 cm−3 range, almost all carbon atoms are electrically activated and at 9×1019 cm−3, 91% are activated. The carbon incorporation efficiency in GaAs layers grown by metalorganic molecular beam epitaxy (MBE) and chemical beam epitaxy (CBE) is lower than that by MBE due to the site-blocking effect of the triethylgallium molecules. In addition, in CBE of GaAs using tris-dimethylaminoarsenic (TDMAAs), the carbon incorporation is further reduced, but it can be increased by cracking TDMAAs. Annealing studies indicate no hydrogenation effect.  相似文献   

9.
In this study, the use of novel, liquid, organic arsenic precursors as substitutes for the highly toxic hydride gas arsine (AsH3) in low pressure metalorganic vapor phase epitaxy (LP-MOVPE) of (GaIn)As lattice matched on InP has been investigated. The model precursors out of the classes of (alkyl)3-nAsHn (n = 0,1,2) are tertiarybutyl arsine (TBAs), ditertiarybutyl arsine (DitBAsH) and diethyltertiarybutyl arsine (DEtBAs). The MOVPE growth has been investigated in the temperature range of 570–650°C using V/III ratios from 2 to 20. The obtained epitaxial layer quality as examined by means of optical and scanning electron microscopy (SEM), high resolution double crystal X-ray diffraction, temperature-dependent van der Pauw-Hall, as well as photoluminescence (PL) measurements, will be compared for the different source molecules. Under optimized conditions almost uncompensated n-type (GaIn)As layers with carrier concentrations below 1 × 1015 cm−3 and corresponding mobilities above 80 000 cm2/V · s have been realized. For TBAs and DitBAsH in combination with the corresponding P sources TBP and DitBuPH, respectively, we have worked out a process parameter area for the growth of layers with device quality, as proven by the realization of a pin-detector structure.  相似文献   

10.
In this paper, we will discuss how the unique growth chemistry of MOMBE can be used to produce high speed GaAs/AlGaAs heterojunction bipolar transistors (HBTs). The ability to grow heavily doped, well-confined layers with carbon doping from trimethylgallium (TMG) is a significant advantage for this device. However, in addition to high p-type doping, high n-type doping is also required. While elemental Sn can be used to achieve doping levels up to 1.5×1019 cm-3, severe segregation limits its use to surface contact layers. With tetraethyltin (TESn), however, segregation does not occur and Sn doping can be used throughout the device. Using these sources along with triethylgallium (TEG), trimethylamine alane (TMAA), and AsH3, we have fabricated Npn devices with 2 μm×10 μm emitter stripes which show gains of ≥ 20 with either ƒt = 55 GHz and ƒmax = 70 GHz or ƒt = 70 GHz and ƒmax = 50 GHz, depending upon the structure. These are among the best RF values reported for carbon doped HBTs grown by any method, and are the first reported for an all-gas source MOMBE process. In addition, we have fabricated a 70 transistor decision circuit whose performance at 10 Gb/s equals or exceeds that of similar circuits made from other device technologies and growth methods. These are the first integrated circuits reported from MOMBE grown material.  相似文献   

11.
Indium phosphide, gallium arsenide phosphide, and aluminum indium phosphide have been deposited by metalorganic vapor-phase epitaxy using tertiarybutylphosphine and tertiarybutylarsine. The effects of growth temperature and V/III ratio on the amount of silicon, sulfur, carbon, and oxygen in InP have been determined. Minimum incorporation was observed at 565 °C and a V/III ratio of 32. In this case, the material contained a background carrier concentration of 2.7×1014 cm−3, and the Hall mobilities were 4970 and 135,000 cm2/V s at 300 and 77 K. The oxygen contamination in AlInP was found to be only 9.0×1015 cm−3 for deposition at 650 °C and a V/III ratio of 35. The relative distribution of arsenic to phosphorus in GaAsyP1−y was determined at temperatures between 525 and 575 °C. The distribution coefficient [(NAs/NP)film/(PTBAs/PTBP)gas] ranged from 25.4 to 8.4, and exhibited an Arrhenius relationship with an apparent activation energy of 1.2 eV.  相似文献   

12.
The influence of oxygen contamination on Si low pressure vapour phase epitaxy (LPVPE) at 800°C in the SiCl2H2−H2 system has been investigated. O2 was added intentionally with partial pressures between 10−8 and 2×10−4 mbar. The quality of the epitaxially grown silicon layers was determined by comparing surface morphology, defect density, Schottky diode characteristics and SIMS measurements. These four parameters are correlated and they reveal a drastic decrease in epitaxial layer quality for O2 pressures above 15×10−6 mbar. The critical oxygen pressure which has been until now considered as a limit for epitaxial growth can therefore be exceeded by one order of magnitude.  相似文献   

13.
Thermally stimulated luminescence (TSL) and infrared (IR) spectroscopy were measured in plasma grown Si1−xGexO2 (x=0, 0.08, 0.15, 0.25, 0.5) with different thicknesses (12–40 nm). A comparison with the TSL properties of thermally grown SiO2 and GeO2 was also performed. A main IR absorption structure was detected, due to the superposition of the peaks related to the asymmetric O stretching modes of (i) Si–O–Si (at ≈1060 cm−1) and (ii) Si–O–Ge (at 1001 cm−1). Another peak at ≈860 cm−1 was observed only for Ge concentrations, x>0.15, corresponding to the asymmetric O stretching mode in Ge–O–Ge bonds. A TSL peak was observed at 70°C, and a smaller structure at around 200°C. The 70°C peak was more intense in all Ge rich layers than in plasma grown SiO2. Based on the thickness dependence of the signal intensity we propose that at Ge concentrations 0.25x0.5 TSL active defects are localised at interfacial regions (oxide/semiconductor, Ge poor/Ge rich internal interface, oxide external surface/atmosphere). Based on similarities between TSL glow curves in plasma grown Si1−xGexO2, thermally grown GeO2 and SiO2 we propose that oxygen vacancy related defects are trapping states in Si1−xGexO2 and GeO2.  相似文献   

14.
The growth and intersubband optical properties of high quality heavily doped p-type GaAs/AlGaAs multiple quantum well (MQW) structures are reported. The MQWs were fabricated by the atmospheric pressure metalorganic vapor phase epitaxy process using liquid CCl4 to dope the wells with C acceptors (Na ≈ 2 × 1019 cm−3). A constant growth temperature was maintained for the entire structure while different V/III ratios were used for the well and barrier regions. By this process it is possible to achieve both high C doping densities in the wells and to simultaneously obtain good quality AlGaAs barriers. Fourier transform infrared spectroscopy measurements on heavily doped 10-period MQW structures reveal a new absorption peak at 2 μm with an effective normal incidence absorption coefficient of 4000 cm−1. Photocurrent measurements on mesa-shaped diodes show a corresponding peak at 2.1 μm. The photodiodes exhibit a symmetrical current-voltage characteristic and a low dark current, which are indicative of a high quality MQW structure and a well-controlled C doping profile. The 2 μm absorption represents the shortest wavelength ever reported for any GaAs/AlGaAs or InGaAs/AlGaAs MQW structure and should be very useful for implementing multicolor infrared photodetectors.  相似文献   

15.
High-performance carbon-doped-base GaAs/AlGaAs heterobipolar transistors (HBTs) were grown by gas-source MBE using only gaseous sources including dopant sources. The AlGaAs emitter layer was doped with Si from uncracked SI2H6 (n = 9 × 1017 cm-3), and the base layer (92.5 nm) was doped with carbon from TMG (p = 4 × 1019 cm-3). From SIMS analysis it was confirmed that a well-defined emitter-base junction with sharp carbon profile was obtained. The base-current ideality factor from the Gummel plot was 1.47, and the emitter-base junction ideality factor was 1.12. A high DC current gain of 53 was obtained at a current density of 4 × 104 A/cm2. The device characteristics of our carbon-doped HBTs were found to be stable under current stress.  相似文献   

16.
The properties and concentrations of oxygen-deficient type structural defects in type III SiO2 glasses implanted with Ti+, Cr+, Mn+, Fe+, or Cu+ to doses from 0.5×1016 to 6×10016 ions/cm2 at an energy of 160 keV have been measured by using vacuum UV and EPR spectroscopies. An intense absorption band centered around 7.5 eV is observed in all the samples except for Cu-implanted ones and is attributed primarily to Si---Si homo-bonds with the bond distance close to that of the Si2H6 molecule. The homo-bond and implanted ion concentrations are of the same order of magnitude in the implanted layers. An E′ type center associated with the homo-bond is observed in all the samples except for Cu-implanted ones. Anomalous behaviors of the Cu-implanted samples are attributed to the formation of Cu-colloids. An enhanced formation of metallic particles or colloids is suggested for the samples implanted with Cr, Mn or Fe to doses higher than 3×1016 ions/cm2.  相似文献   

17.
Lattice-mismatched heteroepitaxy has attracted considerable attention in recent years. A great interest of these systems is the possibility of integrating devices from different materials on a single substrate. 1.3 and 1.5 μm InGaAs(P)/InP laser diodes are essential for optical communication, whereas InP field effect transistor technology is less developed than that of GaAs MESFET. The performances of laser diodes are much more sensitive to a high density of disclocations, so it would be interesting to grow GaAs MESFET on InP for integration with 1.3 and 1.5 μm lasers. Due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP, it is very difficult to grow GaAs epilayers of high quality on it is very difficult to grow of GaAs epilayer high quality on InP substrates due to the large difference of the thermal expansion coefficient and lattice parameter between GaAs and InP. A new method, metalorganic source modulation epitaxy (MOSME), which improves the crystal quality of GaAs epilayers on InP substrates by MOVPE, has been adopted in our laboratory. The lowest full width at half maximum (FWHM) of the double crystal X-ray (DCX) diffraction spectra reaches as low as 120 arcsec for a 5 μm thick layer. Structural properties (misorientation, lattice parameters and crystal quality) of 1.0–5.0 μm thick GaAs layers grown on InP have been measured by DCX diffraction. On GaAs MESFETs grown on InP, we have measured gm = 100 ms/mm. For these transitions, the current gain cut-off frequency (Ft) is around 12 GHz and the maximum frequency of oscillation (Fmax) is higher than 30 GHz.  相似文献   

18.
Yuan Lirong  Yao Guoxing 《Journal of Non》1988,100(1-3):309-315
This study demonstrates that hydrolysis should be carried out in a step manner in gel synthesis. The key to the increase in the amount of water added is the control of the hydrolysis rate of Ti(OC4H9)4. The hydrolysis of Si(OC2H5)4 can be carried out at about 75°C. The amount of added water (γWI), which varied with TiO2 content (in mol%), was about 64–88% of the total amount of added water. The hydrolysis reaction should be performed at room temperature while Ti(OC4H9)4 is added. The total amount of added water (γW) is related to the amount of solvent (R). For example, if TiO2 is 40mol%, γW will vary from 3.2 to 8.0 when R varies from 0.8 to 2.0. The amount of added water was affected by the distribution of solvent in the metal alkoxides. The amount of added water can be increased when RSi(OC2H5)4 = 1, RTi(OC4H9)4 > 1. The rate of rise in temperature of the thermolysis of the dried gel should be less than 10°C per hour, and the heat treatment temperatyre is related to the TiO2 content (in mol%). Gel glasses without devitrification can only be obtained by thermolysis at 600°C from the gel with no less than 20 mol% TiO2.  相似文献   

19.
A systematic study of structural and electrical properties of GaSb and AlGaSb grown on GaAs by metalorganic chemical vapor deposition is reported. In general, the results obtained from surface morphologies, X-ray linewidths and Hall properties are consistent with each other and indicate that the optimal growth conditions for GaSb are at 525°C around V/III = 1. A highest hole mobility of 652 cm2/V · s at RT (3208 cm2/V · s at 77 K) and a lowest concentration of 2.8 × 1016 cm−3 (1.2 × 1015 cm−3 at 77 K) were obtained for GaSb grown under this optimal condition. Compared to the GaSb growth, a smaller V/III ratio is needed for the AlGaSb growth to protect the surface morphology. When Al was incorporated into GaSb growth, mobility decreased and carrier concentration increased sharply. The AlGaSb grown at 600°C had a background concentration about one order of magnitude lower than the AlGaSb grown at 680°C. Room-temperature current-voltage characteristics of GaSb/AlxGa1 − xSb/GaSb show a rectifying feature when Al composition x is higher than 0.3, suggesting a valence-band discontinuity at the AlGaSb/GaSb interface. A leakage current much higher than the value predicted by the thermionic emission theory is observed at 77 K, presumably due to a large number of dislocations generated by the huge lattice mismatch between GaSb and GaAs.  相似文献   

20.
Heavily carbon-doped p-type InxGa1−xAs (0≤x<0.49) was successfully grown by gas-source molecular beam epitaxy using diiodomethane (CH2I2), triethylindium (TEIn), triethylgallium (TEGa) and AsH3. Hole concentrations as high as 2.1×1020 cm−3 were achieved in GaAs at an electrical activation efficiency of 100%. For InxGa1−xAs, both the hole and the atomic carbon concentrations gradually decreased as the InAs mole fraction, x, increased from 0.41 to 0.49. Hole concentrations of 5.1×1018 and 1.5×1019 cm−3 for x = 0.49 and x = 0.41, respectively, were obtained by a preliminary experiment. After post-growth annealing (500°C, 5 min under As4 pressure), the hole concentration increased to 6.2×1018 cm−3 for x = 0.49, probably due to the activation of hydrogen-passivated carbon accepters.  相似文献   

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