AVS 53rd International Symposium
    Electronic Materials and Processing Wednesday Sessions
       Session EM-WeM

Paper EM-WeM1
Growth of GaP on Nanoscopically Roughened (001)Si

Wednesday, November 15, 2006, 8:00 am, Room 2003

Session: New Directions in Compound Semiconductors
Presenter: D.E. Aspnes, North Carolina State University
Authors: I.K. Kim, North Carolina State University
X. Liu, North Carolina State University
D.E. Aspnes, North Carolina State University
Correspondent: Click to Email
The chemical mismatch between III-V and Group IV materials makes the growth of III-V materials on Si substrates problematic. This is true even for GaP, which is nearly lattice-matched to Si. While GaP has been grown on (001)Si at low temperatures of the order of 300°C by organometallic chemical vapor deposition using easily decomposed tertiarybutylphosphine and triethylgallium precursors, higher growth temperatures offer the promise of higher-quality material. However, growth at temperatures of the order of 750°C with phosphine and trimethylgallium (TMG) precursors on standard RCA-cleaned (001)Si substrates yields widely separated protrusions of GaP separated by regions of bare Si. Here, we show that continuous films of GaP can be grown on (001)Si at these higher temperatures if the substrate is nanoscopically roughened in situ prior to deposition. Roughening not only increases the density of nucleation sites but also increases surface area and inhibits the diffusion of mobile species over the substrate surface without compromising the crystalline quality of the substrate, all of which act to promote the growth of continuous overlayers. However, we also find that the nanoroughness of the substrate can propagate through to the GaP surface, complicating the process. We take advantage of our in situ polarimetric diagnostic capabilities to explore the effect of different deposition conditions in real time, which allows us to efficiently optimize conditions with respect to both roughness and deposition. Our best films are obtained when TMG is introduced as pulses well separated in time.