Atmospheric Pressure Chemical Vapor Deposition Growth Window for Undoped Gallium Antimonide
- PDF / 412,022 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 90 Downloads / 207 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Atmospheric pressure chemical vapor deposition growth window for undoped gallium antimonide A. Subekti,a) E. M. Goldys,b) Melissa J. Paterson, K. Drozdowicz-Tomsia, and T. L. Tansley Semiconductor Science and Technology Laboratories, Macquarie University, North Ryde, New South Wales, 2109, Australia (Received 15 October 1997; accepted 17 October 1998)
Metalorganic chemical vapor deposition (MOCVD) GaSb growth using trimethylgallium and trimethylantimony as a function of substrate temperature and VyIII ratio was examined. These parameters were found to have a significant effect on the growth rate and surface morphology of the GaSb films. A phase diagram is used to interpret the effect of these growth parameters on the GaSb film growth. The region of single-phase growth was found to be narrow, falling between 540 and 560 ±C. The optimum growth conditions for the MOCVD growth of GaSb have been determined for a TMGa flow rate of 20 sccm and a carrier gas flow of 8 lymin. The optimum substrate temperature and VyIII ratio were found to be 540 ±C and 0.72, respectively. In these conditions the lowest hole concentration of 5 3 1016 cm23 and the highest room temperature mobility of 500 cm2 V 21 s21 were achieved, accompanied by a steep, well-resolved band edge at 0.72 eV.
I. INTRODUCTION
GaSb epitaxial layers have been grown by liquid phase epitaxy1 and molecular beam epitaxy,2 with metalorganic chemical vapor deposition (MOCVD) more recently established.3–12 MOCVD offers the large area growth and precise control of layer thickness, purity, and doping concentration important in any production technique for semiconductor device structures. Remaining challenges in GaSb growth by MOCVD are related to the narrow range of useful precursor ratios and the need for low growth temperatures. GaSb had been grown by low9–12 and atmospheric3,5–8 pressure MOCVD. The latter has been shown to have the advantage of improved homogeneity of layer thickness, doping, and composition, while our choice of this variant has been further motivated by the work of Haywood et al.3 who report a clear correlation between the mobility maxima and growth pressure. Their highest mobilities were obtained at atmospheric pressure, or slightly above, a finding confirmed by other groups. It is possible to grow good quality GaSb at high growth rates from the standard metalorganic precursors trimethylgallium (TMGa) and trimethylantimony (TMSb), although their thermal decomposition characteristics differ significantly. TMGa is 50% pyrolyzed at 440 ±C18 and TMSb 50% pyrolyzed at 500 ±C13 . The congruent melting point of GaSb is 712 ±C, but it dissociates above about 600 ±C, leading to a relatively narrow a)
Permanent address: Program Fisika Jurusan, MIPA, FKIP Universitas Jember, Jl. Kalimatan IIIy3, Jember, Indonesia. b) Address all correspondence to this author. 1238
http://journals.cambridge.org
J. Mater. Res., Vol. 14, No. 4, Apr 1999
Downloaded: 14 Mar 2015
growth temperature window. Despite these limitations,
Data Loading...
