Relaxed GaP on Si with low threading dislocation density

Ryan D. Hool, Yuji Chai, Yukun Sun, Brendan C. Eng, Pankul Dhingra, Shizhao Fan, Kevin Nay Yaung, Minjoo Larry Lee

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Abstract

We demonstrate a two-step procedure for the growth of relaxed GaP on pseudomorphic GaP/Si templates with a threading dislocation density (TDD) of 1.0-1.1 × 106 cm-2. In lattice-mismatched epitaxy, suppressed dislocation nucleation and unimpeded dislocation glide during relaxation are both critical to achieve a low TDD. Our two-step growth process realizes the former by initiating growth with a thin, low growth temperature (Tgrowth) layer and the latter with a subsequent high-Tgrowth layer. In optimizing the low-Tgrowth layer thickness, we find a trade-off where too little thickness does not suppress dislocation nucleation, while too much thickness takes away the advantage of higher dislocation velocity at high-Tgrowth. Dislocation pileups and trenches are identified as heterogeneous features with a very high local TDD that commonly arise during single-step growth of GaP on Si at high-Tgrowth, and two-step growth virtually eliminates their formation. Overall, this work shows that after initiation at low-Tgrowth, subsequent epitaxy can be performed at high-Tgrowth while avoiding rampant dislocation nucleation, as well as formation of trenches and dislocation pileups.

Original languageEnglish (US)
Article number042102
JournalApplied Physics Letters
Volume116
Issue number4
DOIs
StatePublished - Jan 27 2020

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Hool, R. D., Chai, Y., Sun, Y., Eng, B. C., Dhingra, P., Fan, S., Nay Yaung, K., & Lee, M. L. (2020). Relaxed GaP on Si with low threading dislocation density. Applied Physics Letters, 116(4), [042102]. https://doi.org/10.1063/1.5141122