Amorphous-Se/GaAs –A Novel Heterostructure for Solid-State Devices–

Abstract

Interface properties of an amorphous (a-)Se/GaAs(001) heterostructure made on a Se-stabilized (2×1) GaAs surface are investigated. Photoemission spectroscopy analysis shows that the band alignment is staggered with the valence band discontinuity of -0.27±0.05 eV. Amorphous-Se/GaAs diode current-voltage characteristics also support the staggered alignment. This is suitable for applications to photoelectric devices in which photogenerated holes in GaAs are injected into a-Se for low-noise avalanche multiplication. Capacitance-voltage characteristics of the diode show the presence of interface states near the conduction band edge of GaAs, in agreement with the Fermi-level position measured from photoemission spectroscopy. These pinning states are introduced through the deposition of a-Se, and may be attributed to outdiffused Ga atoms in a-Se.