Accession Number : ADA303265

Title :   Nitride Semiconductors for Ultraviolet Detection.

Descriptive Note : Final technical rept. 1 Jul-31 Dec 95,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Davis, Robert F.

PDF Url : ADA303265

Report Date : DEC 1995

Pagination or Media Count : 57

Abstract : Monocrystalline Al(x)Ga(1-x)N (0.05 < or = x < or = 0.70) thin films, void of oriented domain structures and low-angle boundaries and in the undoped, n-type Si doped (x < or =0.40) and p-ype Mg doped (x < or =0.13) states have been grown via OMVPE directly on 6H-SiC substrates. The surface morphologies were smooth; the FWHM of the DCXRC curves (0002 reflection) were as low as 186 arc sec for the undoped films. Values of the bandgap as a function of composition showed a negative bowing parameter. A new OMVPE system devoted to growth and doping of In(x)Ga(1-x)N alloys and related alloys and a new method for gas source MBE of III-N materials at increased deposition rates have been commissioned. Temperature-dependent PL measurements of undoped GaN films indicated emission from both free and bound excitons. The exciton binding energy to the neutral donor was approx.7 meV. Photoluminescence at 4.2 K on a GaN film with a thickness gradient of .5 mm revealed an energy shift in the band-edge peak, most likely due to strain effects. Photoluminescence of GaN for thickness below .8 mm revealed an increase in the donor-acceptor pair (DAP) emission intensity which is tentatively attributed to an increase in acceptor doping. The use of HCl solutions to clean the surfaces of GaN(0001) yields the lowest O and C concentrations. jg p2

Descriptors :   *SEMICONDUCTORS, *NITRIDES, *ULTRAVIOLET DETECTION, EMISSION, SOURCES, THICKNESS, NEUTRAL, PHOTOLUMINESCENCE, MORPHOLOGY, ENERGY, STRUCTURES, THIN FILMS, INTENSITY, RATES, ORGANOMETALLIC COMPOUNDS, EPITAXIAL GROWTH, SUBSTRATES, ALLOYS, HYDROGEN, GASES, SURFACES, BOUNDARIES, DEPOSITION, NUCLEAR BINDING ENERGY, COPPER, SHIFTING, GALLIUM, TITANIUM, DOPING, N TYPE SEMICONDUCTORS, CLEANING, GOLD, ELECTRON ACCEPTORS, GERMANIUM, INDIUM, SILICON CARBIDES, GRADIENTS, P TYPE SEMICONDUCTORS, COBALT, EXCITONS, LOW ANGLES, MOLECULAR BEAM EPITAXY.

Subject Categories : Electrical and Electronic Equipment
      Inorganic Chemistry
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE