Vacancy-engineering-induced dislocation inclination in III-nitrides on Si substrates

Abstract

The incorporation of point defects into semiconductors could substantially tailor their optical and electrical properties as well as the spin-based quantum properties. In terms of structural properties, however, efforts have seldom been devoted to the relevant aspects. Herein, we propose point defects engineering by intentionally introduced vacancies to improve the structural properties. GaN-on-Si are selected as a paradigm to demonstrate the applicability of this approach. By tuning the growth stoichiometry, nonequilibrium Ga vacancies are intentionally introduced and absorbed by dislocation cores, which leads to dislocation inclination and annihilation in GaN. In addition, this dislocation inclination can proceed without relaxing the compressive lattice stress. These together enable high quality GaN thick layers on Si substrates with dislocation density of $1.6\ifmmode\times\else\texttimes\fi{}{10}^{8}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$ and a record electron mobility of $1090\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}/\mathrm{V}\phantom{\rule{0.16em}{0ex}}\mathrm{s}$ at a carrier density of $1.3\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}{10}^{16}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$. With these advances, a quasivertical GaN Schottky barrier diode with the lowest specific on-resistance of $0.95\phantom{\rule{0.16em}{0ex}}\mathrm{m}\mathrm{\ensuremath{\Omega}}/\mathrm{c}{\mathrm{m}}^{2}$ and highest on/off ratio of ${10}^{10}$ on Si substrates is demonstrated. These results demonstrate the promise of point defect engineering as a strategy to improve the structural properties and pave the way for high-performance III-nitride based electronic and optoelectronic devices on Si platforms.