Accession Number : ADA329115

Title :   Interface Properties of Wide Bandgap Semiconductor Structures.

Descriptive Note : Semiannual technical rept. for 1 Jan-30 Jun 97,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Davis, R. F. ; Bedair, S. ; Bernholc, J. ; Nemanich, R. J. ; Sitar, Z.

PDF Url : ADA329115

Report Date : JUN 1997

Pagination or Media Count : 194

Abstract : On GaN films ICP etched at low power did not differ from unetched GaN. Leakage currents for the low power and unetched GaN were similar to -10V (less than -1nA). The forward and reverse characteristics for 100 micrometer diameter Pt contacts on GaN etched at high power were similar to those of large (150-200 micrometer diameter) unetched GaN contacts . The barrier heights for these contacts were low and the ideality factors high. Molecular dynamics calculations showed that Si and Ge are effective mass donors, and C is an effective mass acceptor in wurtzite GaN. The doping efficiency may be severely limited by self- compensation and formation of nearest-neighbor pairs under certain growth conditions. Samples of GaN were implanted at energies (doses) of 160 KeV or 200 KeV (1e14 cm-2 to 1e15 cm-2) with Si; 120 KeV (1e14 cm-2 to 1e15 cm-2) with Mg; and 180 KeV/130 KeV (5e14cm-2 to 5e15 cm-2 with Ca/P at 25, 550, and 650 deg C. Electrical activation has been observed; however, it was very small in all samples even alter repeated annealing steps. The insulators of SiO2, GaO and AlN were grown or deposited on GaN films. MIS capacitors were fabricated using plasma deposited SiO2. The flatband voltage for the SiO2 was 1.1 V; the calculated fixed oxide charge was 4.1x10(exp11) cm-2. The lineshapes of the Raman E2 mode of AlxGa(1-x)N in the composition range 0<x<1 exhibited significant asymmetry and broadening toward the high energy range. The spatial correlation model accounted for these results. Calculations indicated and X-ray scattering confirmed the absence of long-range order. The relative intensity of the superlattice line was negligible. The line broadening of the E2 mode exhibited a maximum at x = 0.5 indicative of a random disordered alloy system.

Descriptors :   *EPITAXIAL GROWTH, *ION IMPLANTATION, *DOPING, CRYSTAL LATTICES, HETEROJUNCTIONS, DIAMONDS, ENERGY GAPS, ETCHING, FIELD EMISSION, X RAY SCATTERING, SURFACE CHEMISTRY, SCHOTTKY BARRIER DEVICES, SILICON CARBIDES, DILUENTS, GALLIUM NITRIDES.

Subject Categories : Mfg & Industrial Eng & Control of Product Sys
      Crystallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE