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

• Published in: Japanese Journal of Applied Physics Vol. 30; no. 12S; p. 3763
• Main Authors: Takatani, Shinichiro, Takeshi Kikawa, Takeshi Kikawa, Masatoshi Nakazawa, Masatoshi Nakazawa
• Format: Journal Article
• Language: English
• Published: 01.12.1991
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.30.3763

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.