AVS 45th International Symposium
    Electronic Materials and Processing Division Friday Sessions
       Session EM-FrM

Paper EM-FrM1
Optical, Structural, and Morphological Properties of Epitaxial Al@sub x@Ga@sub (1-x)@N(0001) Films Grown by Gas-Source Molecular Beam Epitaxy

Friday, November 6, 1998, 8:20 am, Room 316

Session: Fabrication and Characterization of Semiconductor Device Layers
Presenter: J.E. Van Nostrand, Air Force Research Laboratory
Authors: J.E. Van Nostrand, Air Force Research Laboratory
R.L. Hengehold, Air Force Institute of Technology
K.D. Leedy, Air Force Research Laboratory
M.L. Seaford, Air Force Research Laboratory
D.H. Tomich, Air Force Research Laboratory
C.E. Stutz, Air Force Research Laboratory
Q.-H. Xie, Air Force Research Laboratory
Correspondent: Click to Email
Al@sub x@Ga@sub (1-x)@N/GaN(0001) is a material system of great interest due to its potential for optoelectronic and high temperature electronic applications. However, published studies on the growth and characterization of Al@sub x@Ga@sub (1-x)@N films are limited, and the structural and optical properties of Al@sub x@Ga@sub (1-x)@N films are not well understood. We present optical, microstructural, and morphological results for 0.5 µm thick Al@sub x@Ga@sub (1-x)@N thin solid films on 2.0 µm thick GaN on Al@sub 2@O@sub 3@(0001) grown by gas source molecular beam epitaxy. Films are deposited at 800°C with a 0.5 µm hr@super -1@ growth rate, and ammonia is used for the nitrogen source. High-resolution X-ray diffraction results show deformation of the unit cell in the Al containing layers for x<0.15 due to tensile biaxial strain. Measurement of the evolution of surface morphology as a function of Al mole fraction using atomic force microscopy shows a large increase in surface roughness with increasing Al mole fraction for x<0.15, followed by an order of magnitude decrease in roughness for relaxed films. Microstructural properties such as dislocation type and density as a function of Al mole fraction are systematically evaluated using cross-sectional transmission electron microscopy. Finally, low temperature (6K) cathodoluminescence is used to evaluate the location of the donor-bound exiton in the Al@sub x@Ga@sub (1-x)@N bandgap as a function of Al mole fraction. An approximately linear dependence on x is observed, suggesting the Al@sub x@Ga@sub (1-x)@N bandgap also exhibits a linear dependence on x.