Experimental determination of the valence band offsets of $ZnGe{N}_2$ and $ZnG{e}_{0.94}G{a}_{0.12}{N}_2$ with $GaN$

Abstract

A predicted type-II staggered band alignment with an approximately $1.4eV$ valence band offset at the $ZnGe{N}_2/GaN$ heterointerface has inspired novel band-engineered $III-N/ZnGe{N}_2$ heterostructure-based device designs for applications in high performance optoelectronics. We report on the determination of the valence band offset between metalorganic chemical vapor deposition grown $(ZnGe{)}_{1-x}G{a}_{2x}{N}_2$, for $x=0$ and $0.06$, and $GaN$ using X-ray photoemission spectroscopy. The valence band of $ZnGe{N}_2$ was found to lie $1.45-1.65eV$ above that of $GaN$. This result agrees well with the value predicted by first-principles density functional theory calculations using the local density approximation for the potential profile and quasiparticle self-consistent GW calculations of the band edge states relative to the potential. For $(ZnGe{)}_{0.94}G{a}_{0.12}{N}_2$ the value was determined to be $1.29eV$, $10-20\%$ lower than that of $ZnGe{N}_2$. The experimental determination of the large band offset between $ZnGe{N}_2$ and $GaN$ provides promising alternative solutions to address challenges faced with pure III-nitride-based structures and devices.