Accession Number : ADA267561


Title :   Pseudomorphic Semiconducting Heterostructures from Combinations of AIN, GaN and Selected SiC Polytypes: Theoretical Advancement and Its Coordination with Experimental Studies of Nucleation, Growth, Characterization and Device Development


Descriptive Note : Semiannual rept. 1 Jan-30 Jun 93,


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


Personal Author(s) : Davis, Robert F ; Ailey, K S ; Kern, R S ; Patterson, R ; Tanaka, S


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a267561.pdf


Report Date : Jun 1993


Pagination or Media Count : 33


Abstract : Solid solutions and pseudomorphic heterostructures of AIN and SiC have been grown on vicinal alpha (6H)-SiC substrates via plasma-assisted, gas- source molecular beam epitaxy at 1050 deg C. Reflection high energy electron diffraction, high resolution TEM and Auger depth profiling show the films to be monocrystalline and to possess the desired chemical compositions. The solid solutions have the wurtzite structure. The multilayers have the following phases: alpha (6H)-SiC substrate, 2H-AIN and 3C-SiC. Chemical interdiffusion between alpha (6H)-SiC wafers and epitaxially deposited 2H-AIN films are under investigation within the temperature range of 1500 deg C to 1700 deg C. Scanning Auger spectroscopy and XTEM is being used to determine the diffusion profiles and the occurrence of new phases. The Auger data and electron energy loss measurements are in disagreement. Additional diffusion and segregation research is under way to resolve this conflict. Superlattices of GaN/AIN on sapphire and SiC have been extensively investigated via HRTEM. Below the critical thickness, AIN only contains threading dislocations emanating from the misfit dislocations; above this thickness, defects parallel to the growth surface greatly increase. Deposition of GaN on sapphire or SiC results in a larger number of threading dislocations caused by the large misfit as well as a high concentration of dislocations parallel to the growth surface. Both types of defects are decreased in density if the GaN is deposited on AIN.... Pseudomorphic structures, 3C-SiC, 6H-SiC, GaN, AIN, Gas-source molecular beam epitaxy, Chemical interdiffusion, Threading dislocations, Misfit dislocations, Critical thickness


Descriptors :   *SEMICONDUCTORS , *NITRIDES , *ALUMINUM , *GALLIUM , SCANNING , DENSITY , MEASUREMENT , TEMPERATURE , THICKNESS , CRYSTAL STRUCTURE , SPECTROSCOPY , REFLECTION , DEPOSITION , HIGH ENERGY , SURFACES , CHEMICAL COMPOSITION , GASES , PHASE , MOLECULAR BEAMS , DEPTH , HIGH RESOLUTION , DEFECT ANALYSIS , SILICON CARBIDES , SOLID SOLUTIONS , AUGERS , ELECTRON DIFFRACTION , WAFERS , DIFFUSION , DIFFRACTION , DISLOCATIONS , PROFILES , ELECTRON ENERGY , SAPPHIRE , NUCLEATION , LAYERS , SUPERLATTICES , FILMS , SINGLE CRYSTALS , EPITAXIAL GROWTH , SUBSTRATES


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Crystallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE