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Ion-depth profiling with Auger electron spectroscopy has been used to measure the interface width of MBE, VPE, and LPE At Gal _ x As-GaAs heterojunctions purposely fabricated to minimize interface width. By profiling the MBE structures with 250-eV Ar+ ions, it was possible to experimentally measure an interface width (10--90% Al p-p height) of -15 A. The measured interface width of VPE and LPE Alx Gal _ x As-GaAs was found to be -65 and 100 A, respectively. Since rectification has not in the past been observed in n-n AlxGal_xAs-GaAs heterojunctions, n-n AlxGal_xAs-GaAs heterojunctions were fabricated in this study to enhance the presence of the conductionband discontinuity (enhancing any possible rectification) by growing these heterojunctions from lightly doped (10 15 _10 16 cm -3) material; however, these heterojunctions did not exhibit rectification, in agreement with previous studies. The interface widths of these samples were then measured and found to be much smaller than present theories require to remove the barrier. Since compositional grading is not large enough to explain the absence of rectification, several alternative explanations to the absence of rectification are discussed.

The rapid thermal annealing (RTA) of implanted layers in semi‐insulating gallium arsenide encapsulated with silicon nitride has been investigated and compared with conventional hot wall furnace annealing. The evaluation was based on comparisons of the electrical characteristics of MESFET's including channel sheet resistance, pinchoff voltage, saturation drain current, and isolation sheet resistance. The results show that a high degree of uniformity and reproducibility of device characteristics over full 2 and 3 in. wafers can be obtained using rapid thermal annealing. Moreover, the rapid thermal annealing process has resulted in reduced damage to the silicon nitride encapsulating dielectric, and increased carrier mobility in the active layers, making it a desirable alternative for the production of gallium arsenide integrated circuits.