Accession Number : ADA254278


Title :   Atomic Approaches to Defect Thermochemistry


Descriptive Note : Final rept. 1 Apr 1989-31 Mar 1992


Corporate Author : OREGON STATE UNIV CORVALLIS DEPT OF ELECTRICAL AND COMPUTER ENGINEERING


Personal Author(s) : Van Vechten, James A ; Wager, John F


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a254278.pdf


Report Date : 30 Apr 1992


Pagination or Media Count : 250


Abstract : We have achieved insight into the role of H in semiconductor crystal growth in processes such as organometallic chemical vapor deposition, OMCVD. If allowed, H will compensate shallow dopants and suppress the formation of other compensators when the Fermi level moves significantly from the intrinsic level at growth or processing temperatures, T. This can be a great advantage because the H can be removed at low T with no rearrangement of other atoms. This has led to the first attainment of good p-type GaN and to improvement of n-type GaN. It should work for any semiconductor. We have improved the thermodynamic analysis of heterojunction band offsets as functions of T and strain. We have done the first fundamental studies of the diffusion equation with boundary conditions appropriate for crystal growth and diffusion and obtained major insights. We devised a simple new experiment to study interstitial impurity diffusion in semiconductors with striking results. We demonstrated that host interstitials play no role in thermal in Si or GaAs and similar low ionicity crystals and have explained the 'U-shaped' profile of transition metal impurities. We have verified that the DX center can be getter out of AlGaAs without reducing donor concentration and studied its properties by various capacitance transient. We have characterized the aging and charge trapping properties of ZnS ACTFEL display materials. We have calculated the entropy of atomic hopping.


Descriptors :   *THERMODYNAMICS , *THERMOCHEMISTRY , *DEFECT ANALYSIS , TRANSIENTS , IONS , METALS , MATERIALS , GALLIUM ARSENIDES , HETEROJUNCTIONS , CHEMICAL VAPOR DEPOSITION , CRYSTALS , CRYSTAL DEFECTS , PROFILES , DEPOSITION , BOUNDARIES , HYDROGEN , INTERSTITIAL , IMPURITIES , SEMICONDUCTORS , ATOMS , GETTERS , COMPENSATORS , CAPACITANCE , ENTROPY , CRYSTAL GROWTH , EQUATIONS , DOPING , DIFFUSION , TRANSITIONS , SILICON , TRAPPING(CHARGED PARTICLES) , ORGANOMETALLIC COMPOUNDS , ALUMINUM GALLIUM ARSENIDES , PROCESSING , TEMPERATURE , TRANSITION METALS , AGING(MATERIALS)


Subject Categories : Physical Chemistry
      Crystallography
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE