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

Research output: Contribution to journalArticle


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
Issue number4
StatePublished - Jan 27 2020


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].