Growth of InSb on GaAs Substrates Using InAlSb Buffers for Magnetic Field Sensor Applications
- PDF / 331,816 Bytes
- 6 Pages / 418.68 x 637.2 pts Page_size
- 14 Downloads / 186 Views
FOR MAGNETIC FIELD SENSOR APPLICATIONS R. M. Biefeld and J. D. Phillips, Sandia National Laboratories, Albuquerque, NM 87185-0601
ABSTRACT We report the growth of InSb on GaAs using InAISb buffers of high interest for magnetic field sensors. We have grown samples by metal-organic chemical vapor deposition consisting of -0.55gm thick InSb layers with resistive InAlSb buffers on GaAs substrates with measured electron mobilities of -40,000 cm2/V.s. We have investigated the In,-.AlxSb buffers for compositions x5 minutes) between the growth of layers containing either TTBA1 or TDMASb. Hydrogen was used as the carrier gas at a total flow of 14.5 slpm, the susceptor rotation was 1100 rpm, and growth was done at 70 Torr. Samples were grown on semi-insulating GaAs consisting of varying compositions of InAlSb layers both with and without an InSb layer on top for comparison of electronic properties and surface morphology. Additional samples of InAlSb were grown on InSb substrates to determine the alloy composition. Prior to In(Al)Sb growth, 100nm GaAs buffers were grown at 630'C before cooling to growth temperature. In addition, bulk GaAs growths were performed prior to each growth run to replicate growth conditions as best as possible. Without the intermediate GaAs growths, the InSb/InAlSb growths were not repeatable, possibly from chamber conditions or material interaction from the susceptor. The InSb growth temperature, growth rate, and TDMASb/TMIn vapor phase ratio were 400'C, 0.5grm/hour, and 1.0, respectively. The InAlSb growth temperature, growth rate, and TESb/(TTBAI+TMIn) vapor phase ratio were 440'C, 0.65gjm/hour, and 4.0-5.0, respectively. During purges transistioning from InAlSb to InSb growth, a thin cap (-5nm) of InSb using TMIn and TESb was grown prior to the purge and at 1 minute intervals during the purge to passivate the surface. Growth runs were monitored using in situ reflectance to evaluate surface morphology development[ 10]. Sample thicknesses were measured using a groove technique. Room temperature Hall measurements using the Van der Pauw technique were used to determine the electron mobility and majority carrier type and concentration. Double crystal x-ray diffraction (DCXRD) (004) and (335) reflections were used to determine InAlSb alloy composition by correcting for residual strain in the layers.
60 Downloaded from https://www.cambridge.org/core. Columbia University Libraries, on 02 Aug 2017 at 12:53:43, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-607-59
5x10 4
E 4x10 C.)_ .j0
4
W3xO
4
2x10 0.5
0.7
0.9
1.1
1.3
1.5
1.7
InSb thickness (micron) Figure 2: Electron mobility of InSb layers of varying thickness grown on GaAs substrates.
RESULTS AND DISCUSSION The growth of InSb on GaAs was examined to optimize growth conditions to ensure good surface morphology and electron mobility. We have used a predeposition of TMIn for 2-5 seconds prior to introducing TDMASb to the reactor, a technique previously reported,
Data Loading...
