Accession Number : ADA322895

Title :   Research Related to the Development, Fabrication and Characterization of UV Detectors and Cold Cathode Devices.

Descriptive Note : Annual rept. 1 May-31 Dec 96,

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

Personal Author(s) : Davis, R. F. ; Bremser, M. D. ; Hanser, D. ; Nam, O. H. ; Perry, W.

PDF Url : ADA322895

Report Date : DEC 1996

Pagination or Media Count : 50

Abstract : Selective growth of GaN and Al(0.2)Ga(0.8)N has been conducted on stripe and circular patterned GaN/AlN/6H-SiC(0001) multilayer substrates. Prismatic morphology with (1-101) side facets was observed on 3 micrometers wide stripes for both materials. Hexagonal pyramid arrays of undoped GaN and Si-doped GaN were achieved on 5 micrometers circular patterns. Field emission measurements of the resulting Si-doped GaN pyramids exhibited a turn-on field of 25V/micrometers for an emission current of 10.8 nA at an anode-to-sample distance of 27 micrometers. Thin films of Si doped Al(x)Ga(1-x)N (0.03 <= x <= 0.42) were deposited on on-axis 6H-SiC(0001) substrates at 1100 deg C using a 0.1 micrometers A1N buffer layer for electrical isolation. Hall effect and CL measurements were used to characterize the electrical and optical properties of these films, respectively. Alloys having the compositions of Al(0.08)Ga(0.92)N and Al(0.42)GA(0.58)N exhibited mobilities of 110 and 14 /cu cm/V-s at a carrier concentrations of 9.6e18 and 5.0e17 /cu cm, respectively. Acceptor doping of Al(x)Ga(1-x)N for x <= 0.08 was also achieved for films deposited at 1050 deg C. The growth of GaN and In(0.22)Ga(0.27)N thin films on 6H-SiC(0001) substrates each containing a high temperature AIN buffer layer has been achieved using a second and more novel OMVPE reactor designed specifically to improve the flow dynamics of the film deposition process. Donor (Si) doping of GaN was achieved with doping levels of 5E16-3E18 /cu cm. Growth of GaN in H2 and N2 was accomplished with the two main differences being stronger PL intensity and slower growth rate for the films grown in N2. Narrow and bright photoluminescence was observed both at room temperature and 12K.

Descriptors :   *GALLIUM ARSENIDES, *ULTRAVIOLET DETECTORS, *COLD CATHODE TUBES, CRYSTAL LATTICES, PHOTOLUMINESCENCE, THIN FILMS, NITRIDES, SCHOTTKY BARRIER DEVICES, CRYSTAL GROWTH, POISSON RATIO, EXCITONS, FIELD EMISSION TUBES, PRISMATIC BODIES, PYRAMIDS(GEOMETRY).

Subject Categories : Electrical and Electronic Equipment
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE