Incorporation of Magnesium into GaN Regulated by Intentionally Large Amounts of Hydrogen during Growth by MOCVD

TL;DR

This study demonstrates that increasing hydrogen flow during MOCVD growth of Mg-doped GaN significantly influences Mg incorporation, resulting in electrically active acceptors without thermal activation.

Contribution

It reveals how large hydrogen flows during MOCVD can regulate Mg incorporation and activation in GaN, a novel approach to improve doping efficiency.

Findings

Room-temperature hole concentration of ~2×10^{17} cm^{-3} achieved without thermal activation.

Large hydrogen flow (25 slm) affects Mg incorporation and complex formation.

Hydrogen flow influences MgH complex coexistence with active MgGa acceptors.

Abstract

Metalorganic chemical vapor deposition (MOCVD) of GaN layers doped with Mg atoms to the recognized optimum level of [Mg] $\sim2 \times 10^{19}$ cm$^{-3}$ has been performed. In a sequence of MOCVD runs, operational conditions, including temperature and flow rate of precursors, have been maintained except for intentionally larger flows of hydrogen carrier gas fed into the reactor. By employing the largest hydrogen flow of 25 slm in this study, the performance of the as-grown Mg-doped GaN layers has been certified by a room-temperature hole concentration of $p\sim2 \times 10^{17}$ cm$^{-3}$ in the absence of any thermal activation treatment. Experimental evidence is delivered that the large amounts of hydrogen during the MOCVD growth can regulate the incorporation of the Mg atoms into GaN in a significant way so that MgH complex can co-exist with a dominant and evidently electrically active isolated MgGa acceptor.