Band alignment study of lattice-matched In0.49Ga0.51P and Ge using x-ray photoelectron spectroscopy

Abstract

Lattice-matched In0.49Ga0.51P was grown on a p-type Ge(100) substrate with a 10° off-cut towards the (111) by low temperature molecular beam epitaxy, and the band-alignment of In0.49Ga0.51P on Ge substrate was obtained by high resolution x-ray photoelectron spectroscopy. The valence band offset for the InGaP/Ge(100) interface was found to be 0.64 ± 0.12 eV, with a corresponding conduction band offset of 0.60 ± 0.12 eV. The InGaP/Ge interface is found to be of the type I band alignment.

InGaP grown on Ge (100) by molecular beam epitaxy: a spectroscopic ellipsometry study

“…In x Ga 1−x P alloy, which is lattice-matched to GaAs at x=0.49 and can be lattice-matched to Ge at x=0.50, has applications in multi-junction solar cells [1]. InGaP is reported to form a type-I band alignment with Ge, offering large valence and conduction band offsets (∼0.6 eV) with respect to Ge [2]. As reported for Ge p-metal-oxide-semiconductor-field-effect-transistors (MOSFETs) and n-MOSFETS capped with a thin latticematched InAlP layer [3], InGaP instead of InAlP could also lead to confinement of electrons and holes within the Ge channel.…”