Fabrication of high sensitivity thin-film indium antimonide magnetoresistors

A method is described for fabricating high-sensitivity thin film of InSb. The fabrication procedure consists of the sequential deposition of chromium, antimony and indium. The films are then heat treated to thermo-chemically produce polycrystalline InSb films. The free-electron mobility of these films is found to be 5.4 × 10⁴ cm²/V. sec, and the free carrier density to be 10¹⁶ cm^?3.Magnetoresistors were fabricated from these films with addition of indium, Hall-voltage shorting strips. The magnetoresistance sensitivity of these resistors was found to be 45 per cent K G, which compares very favourably with that obtained from single crystal InSb resistors.     

InSb,GaSb, and GaInSb grown using trisdimethylaminoantimony

GalnSb alloys as well as the constituent binaries InSb and GaSb have been grown by organometallic vapor phase epitaxy using the new antimony precursor trisdimethylaminoantimony (TDMASb) combined with conventional group III precursors trimethylindium (TMIn) and trimethylgallium (TMGa). InSb layers were grown at temperatures between 275 and 425°C. The low values of V/III ratio required to obtain good morphologies at the lowest temperatures indicate that the pyrolysis temperature is low for TDMASb. In fact, at the lowest temperatures, the InSb growth efficiency is higher than for other antimony precursors, indicating the TDMASb pyrolysis products assist with TMIn pyrolysis. A similar, but less pronounced trend is observed for GaSb growth at temperatures of less than 500°C. No excess carbon contamination is observed for either the InSb or GaSb layers. Ga_1-xIn_xSb layers with excellent morphologies with values of x between 0 and 0.5 were grown on GaSb substrates without the use of graded layers. The growth temperature was 525°C and the values of V/III ratio, optimized for each value of x, ranged between 1.25 and 1.38. Strong photoluminescence (PL) was observed for values of x of less than 0.3, with values of halfwidth ranging from 13 to 16 meV, somewhat smaller than previous reports for layers grown using conventional precursors without the use of graded layers at the interface. The PL intensity was observed to decrease significantly for higher values of x. The PL peak energies were found to track the band gap energy; thus, the luminescence is due to band edge processes. The layers were all p-type with carrier concentrations of approximately 10¹⁷ cm³. Transmission electron diffraction studies indicate that the Ga_0.5In_0.5 Sb layers are ordered. Two variants of the Cu-Pt structure are observed with nearly the same diffracted intensities. This is the first report of ordering in GalnSb alloys.     

Large scale production of indium antimonide film for position sensors in automobile engines

We use low pressure MOVPE to grow indium antimonide films on groups of eight 3 inch GaAs wafers per run. The films are used for the production of magnetoresistive position sensors for the car industry. To meet the narrow specifications for automotive components, the standard deviation of the sheet resistivity, and the thickness of the films have been reduced below 1.5%. This uniformity is the result of an optimization process encompassing the determination of the best susceptor temperature and the optimum flow. The gas velocity was found to have a large impact on the uniformity of the layers. Rotation of the wafers and the use of an optimum gas velocity results in extremely uniform layers.     

The effect of gas temperature on the growth of InP by atomspheric pressure metal-organic chemical vapor deposition using trimethyl indium and PH3 sources

The growth of InP by atmospheric pressure Metal-Organic Chemical Vapor Deposition using trimethyl indium (TMIn) and PH₃ sources is demonstrated. No evidence was found to suggest depletion of TMIn due to a TMIn-PH₃ reaction in the gas phase. It was found, however, that TMIn can, under certain growth conditions, be significantly depleted due to premature gas phase pyrolysis. Decreasing the gas temperature by either increasing the total flow rate or by using a lower thermal conductivity gas was found to decrease the amount of TMIn gas phase pyrolysis and increase the growth rate. It was also found that as the gas becomes cooler and the reactants are used more efficiently in the epitaxial growth, the film morphology improves significantly to a point at which smooth, specular surfaces can be routinely grown. * Work performed while at AT&T Bell Laboratories.     

The effect of organometallic vapor phase epitaxial growth conditions on wurtzite GaN electron transport properties

The growth issues known to effect the quality of GaN organometallic vapor phase epitaxial films are reviewed and the best 300Kmobility vs electron concentration data are discussed. The data probably represent transport properties intrinsic to films grown on sapphire. From the results of Hall measurements, the unintentional donor in high quality GaN films cannot be Si since the donor ionization energy is much larger than that of films intentionally doped with Si (36 vs 26 meV). Electrical properties of a doped channel layer are shown not to be significantly different from those of thick films which implies a viable technology for conducting channel devices. It is argued that 77K Hall measurements are a useful indicator of GaN film quality and a compilation of unintentionally and Si doped data is presented. The 77K data imply that, at least over a limited range, Si-doping does not appreciably change the compensation of the GaN. The 77K data indicate that the low mobilities of films grown at low temperatures are probably not related to dopant impurities.     

Electrical properties of nuclear-doped indium antimonide

The possibility of nuclear doping of indium antimonide over a wide range of concentrations (5×10¹⁴–10¹⁸ cm⁻³) by irradiation with reactor neutrons is investigated; the effect of irradiation and subsequent heat treatments on the electrical parameters of the material is investigated. A comparative analysis of the quality of nuclear-doped and conventional InSb is used to demonstrate the possibility of the practical use of this nuclear-doped material. Fiz. Tekh. Poluprovodn. 33, 774–777 (July 1999)     

Studies of the emission from indium antimonide

Experimental studies on the radio-frequency emission-- from InSb under the influence of electric and magnetic fields in the range of 10 MHz to 10 GHz, including the effect of temperature variations around 77° K, are presented. Indications of very weak emission for a narrow range of electric fields in the absence of a magnetic field are observed.     

Growth and characterization of undoped and N-type (Te) doped MOVPE grown gallium antimonide

The growth of GaSb by MOVPE and itsn-type doping using a dimethyltellurium dopant source are investigated. The results of growth rate, morphology and Te incorporation as a function of growth parameters are given. Increasing growth temperature and V/III reactant ratio were found to reduce the Te incorporation. The lowest Hall carrier concentrations obtained at room-temperature, onp-type andn-type MOVPE GaSb are respectively:p _H= 2.2 × 10¹⁶cm⁻³ with a Hall mobility ofμ _H= 860 cm²/V.s andn _H= 8.5 × 10¹⁵cm⁻³ withμ _H= 3860 cm²/V.s. Furthermore, Hall mobilities as high as 5000 cm²/V.s were measured onn-type GaSb samples.     

Surface passivation of backside-illuminated indium antimonide focalplane array

A novel surface passivation tailored to a two-dimensional array of small-area, gate-controlled InSb photovoltaic diodes fabricated on etch-thinned bulk InSb wafers, with backside illumination, is presented. The surface passivation is based on a controlled surface treatment that reduces the native oxide and is followed by photon-assisted deposition of SiO_x. Thinned bulk n-type InSb with (111) orientation forms two distinctive types of interface on the In and Sb faces, respectively. The In face forms an accumulated interface with reduced surface recombination velocity. The Sb face forms a slightly accumulated interface, with a relatively small concentration of fast and slow surface states. The current-voltage and differential resistance-voltage characteristics of implanted p⁺-n photodiodes exhibit nearly flat behavior up to 1-V reverse bias with reduced leakage currents. The R_o×A product of small-geometry diodes is 5×10⁴ Ω-cm² at 77 K     

Non-rectifying contacts to indium antimonide by immersion plating

Ohmic contacts to high resistivity indium antimonide have been made by displacement plating of copper. Some relevant facts regarding the plating process are presented.     

Growth of order/disorder heterostructures in GaInP using a variation in V/III ratio

CuPt ordering, resulting in formation of a natural monolayer {111} superlattice, occurs spontaneously during organometallic vapor phase epitaxial growth of Ga_0.52In_0.48P. The degree of order is found to be a function of the input partial pressure of the phosphorus precursor (P_P) during growth. This is thought to be mainly due to the effect of P_P on the surface reconstruction. A change in order parameter is associated with a change in the bandgap energy. Thus, a practical application of ordering is the production of a heterostructure by simply changing the flow rate of the P precursor during growth. Examination of transmission electron microscopy data and photoluminescence spectra indicates that order/disorder (O/D) (really less ordered on more ordered) and D/O heterostructures formed by growth using PH₃ at a temperature of 620°C are graded over several thousands of Å: The ordered structure from the lower layer persists into the upper layer. Similar results were obtained at 620°C when the first layer was grown using PH₃ (V/III=160) and the second using tertiarybutylphosphine (TBP) (V/III=5). The use of a temperature of 670°C to produce heterostructures using either PH₃ or TBP yields a totally different behavior. Abrupt D/O and O/D heterostructures can be produced by changing P_P during the growth cycle. The cause of this difference in behavior is not entirely clear. However, it appears to be related to a very slow change in the surface reconstruction, measured using surface photo absorption, when the PH₃ partial pressure is changed at 620°C.     

An experimental study of the indium antimonide thin film transistor

In this paper a survey is given of our experimental investigations on the InSb thin film transistor (TFT). The best characteristics were obtained on a two-sided thin film transistor, made by flash evaporations of InSb on a heated substrate of 250°C, followed by an annealing at 350°C for 30 minutes. Furthermore it was found that the presence of minority carriers obstruct the saturation of the transistor characteristics at room temperature. This negative influence of the minority carriers is weakened at lower temperatures, which makes the InSb TFT more attractive for operations in a cryogenic environment.     

Growth of GaInP/GaAsP short period superlattices by flow modulation organometallic vapor phase epitaxy

One disadvantage of the GalnP/GaAs system is the difficulty often encountered in synthesizing the quaternary material GalnAsP, required to span the intermediate bandgap range (1.42–1.91 eV). Recent studies report on an extensive miscibility gap in this alloy. In this study, we investigate an alternative approach to the growth of material within this bandgap range. We have grown by flow-modulation organometallic vapor phase epitaxy, GalnP/GaAsP superlattices with periods ranging from 80 to 21Å. These are the first reported short-period superlattices in this material system. Effects of superlattice (SL) period, growth temperature, and phosphorous composition in the wells were studied by photoluminescence, high resolution x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The effect of growth temperature on the structural quality of the SLs is correlated to ordering effects in the GalnP layers. Variations in the P composition and the SL period result in a shift in the room temperature bandgap emission from 1.51 to 1.74 eV. Strain-compensated structures have been realized by growing the SL barriers in compression.     

Electrical and structural characterization of GaAs vertical-sidewall epilayers grown by atomic layer epitaxy

Electrical and structural measurements have been performed on novel test structures incorporatingp-type GaAs epilayers grown by organometallic vapor phase atomic layer epitaxy on the vertical sidewalls of semi-insulating GaAs rods formed by ion-beam-assisted etching. Preliminary results indicate that the vertical-sidewall epilayers have excellent crystal quality and sufficient electrical quality to support a sidewall-epitaxy device technology. Some examples of candidate electronic, electrooptic, and photonic devices for vertical-sidewall fabrication are FETs, resistors, waveguides, modulators, and quantum-wire and quantum-dot lasers.     

锑化铟晶体空位缺陷的正电子湮灭研究

锑化铟晶体材料的电学性能是影响最终制备的红外探测器件性能的关键因素。材料内部的杂质以及点缺陷特别是空位缺陷会极大的影响材料的电学性能,有时甚至会导致材料反型。本文利用正电子湮灭谱对锑化铟晶体材料的空位缺陷类型进行了研究,同时还对不同晶体生长拉速、导电类型晶体材料的正电子湮灭寿命进行分析。结果表明其内部主要为VIn型空位缺陷,且在一定拉速范围内,正电子湮灭寿命基本无变化,此外空位缺陷也不是导致N型锑化铟晶体材料导电类型反型的主要原因。     

Methods for reducing deep level emissions from ZnSe grown by organometallic vapor phase epitaxy

Methods for reducing deep level emission from ZnSe layers grown by photo-assisted organometallic vapor phase epitaxy were studied using photo-luminescence. A number of approaches to achieve reductions in deep level emissions were investigated. One of them was the use of a flow modulation technique. Reduction in the deep level emissions was observed when the layers were annealed under zinc-rich conditions during this growth process. The effect of cadmium as an isoelectronic dopant in ZnSe was also studied. It was observed that “doping” levels of cadmium resulted in considerable reduction in deep level emissions from ZnSe layers. Layers were grown under different II/VI ratios, and compared to cadmium doped layers of similar ratios. Reduction in deep level emissions were observed in all cadmium doped layers. Cadmium, therefore, seems to be the most promising isovalent dopant for reducing the deep level emissions in ZnSe.     

GaAs基InAs/AlSb二维电子气结构的生长优化

采用分子束外延设备 (MBE) , 外延生长了InAs/AlSb二维电子气结构样品.样品制备过程中, 通过优化AlGaSb缓冲层厚度和InAs/AlSb界面厚度、改变AlSb隔离层厚度, 分别对比了材料二维电子气特性的变化, 并在隔离层厚度为5nm时, 获得了室温电子迁移率为20500cm2/V·s, 面电荷密度为2.0×1012/cm2的InAs/AlSb二维电子气结构样品, 为InAs/AlSb高电子迁移率晶体管的研究和制备提供了参考依据.     

Quantum efficiency and crosstalk of an improvedbackside-illuminated indium antimonide focal-plane array

The quantum efficiency and crosstalk of backside-illuminated indium antimonide photodiodes in hybrid focal plane arrays are calculated. An improved structure with crosswise ohmic contacts at the backside of the thinned InSb substrate is described. The simulations predict a significant reduction in the crosstalk while retaining high quantum efficiency     

Growth of high-quality GaSb by metalorganic vapor phase epitaxy

The growth of nominally undoped GaSb layers by atmospheric pressure metalorganic vapor phase epitaxy on GaSb and GaAs substrates is studied. Trimethylgallium and trimethylantimony are used as precursors for the growth at 600°C in a horizontal reactor. The effect of carrier gas flow, V/III-ratio, and trimethylgallium partial pressure on surface morphology, electrical properties and photoluminescence is investigated. The optimum values for the growth parameters are established. The carrier gas flow is shown to have a significant effect on the surface morphology. The optimum growth rate is found to be 3–8 μm/ h, which is higher than previously reported. The 2.5 μm thick GaSb layers on GaAs are p-type, having at optimized growth conditions room-temperature hole mobility and hole concentration of 800 cm² V⁻¹ s⁻¹ and 3·10¹⁶ cm^-3, respectively. The homoepitaxial GaSb layer grown with the same parameters has mirror-like surface and the photoluminescence spectrum is dominated by strong excitonic lines.     

Research of mechanical stresses in irradiated tin-doped silicon crystals

An optical method of registration of mechanical stresses in undoped and tin-doped silicon samples is offered. Influence of electron irradiation on energy 5 MeV and high-temperature treatment at a 723 K on residual stresses in a silicon lattice was analyzed in the paper. The proposed method is based on а modulation of polarization of laser radiation transmitted through the anisotropic area and the definition of its anisotropy parameters by means of this modulation. The modulation polarimetry technique is an express method with high detection and resolution. The method allows identifying residual stresses in samples in absolute units with a resolution of 1·10⁻⁴ MPa.