Molecular beam epitaxy of GaN(0001) utilizing NH{sub 3} and/or NH{sup +}{sub {ital x}} ions: Growth kinetics and defect structure
- Materials Science Department, the Coordinated Science Laboratory, and the Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
Gas-source molecular beam epitaxy (GS-MBE), utilizing Ga and NH{sub 3}, and reactive-ion MBE (RIMBE), incorporating both thermal NH{sub 3} and low-energy NH{sup +}{sub {ital x}} ions, were used to grow single crystal GaN(0001) layers on Al{sub 2}O{sub 3}(0001) at temperatures {ital T}{sub {ital s}} between 700 and 850 {degree}C with deposition rates of 0.2--0.5 {mu}m h{sup {minus}1}. The RIMBE experiments were carried out with incident NH{sup +}{sub {ital x}}/Ga flux ratios {ital J}{sub NH{sup +}{sub {ital x}}}/{ital J}{sub Ga}=1.9--3.2 and NH{sup +}{sub {ital x}} acceleration energies {ital E}{sub NH{sup +}{sub {ital x}}}=45--90 eV. Plan-view and cross-sectional transmission electron microscopy analyses showed that the primary defects in the GS-MBE films were threading dislocations having either pure edge or mixed edge/screw characteristics with Burgers vectors {bar b}=1/3{l_angle}2{bar 1}{bar 1}0{r_angle}, basal-plane stacking faults with displacement vectors {bar R}=1/6{l_angle}02{bar 2}3{r_angle}, and prismatic stacking faults with {bar R}=1/2{l_angle}{bar 1}101{r_angle}. In the case of RIMBE films, no stacking faults or residual ion-induced defects were observed with {ital E}{sub NH{sup +}{sub {ital x}}}=45 eV and {ital T}{sub {ital s}}{ge}800 {degree}C. However, increasing {ital E}{sub NH{sup +}{sub {ital x}}} to {ge}60 eV at {ital T}{sub {ital s}}=800 {degree}C gave rise to the formation of residual ion-induced point-defect clusters observable by transmission electron microscopy (TEM). Increasing {ital T}{sub {ital s}} to 850 {degree}C with {ital E}{sub NH{sup +}{sub {ital x}}}{ge}60 eV resulted in the ion-induced defects aggregating to form interstitial basal and prismatic dislocation loops, whose number densities depended upon the ion flux, with Burgers vectors 1/2{l_angle}0001{r_angle} and 1/3{l_angle}2{bar 1}{bar 1}0{r_angle}, respectively. (Abstract Truncated)
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 249414
- Journal Information:
- Journal of Vacuum Science and Technology, A, Vol. 13, Issue 5; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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