Gate metal induced reduction of surface donor states of AlGaN/GaN heterostructure on Si-substrate investigated by electroreflectance spectroscopy
Abstract
The surface donor state of AlGaN/GaN heterostructure on Si-substrate was investigated at the presence of Schottky gate metal (Au,Ni) on the surface by using electroreflectance spectroscopy. The sheet carrier density of two-dimensional electron gas (2DEG) decreased significantly from 1.03×1013cm-2 to 5.74×1012cm-2 for Au and from 1.03×1013cm-2 to 3.68×1012cm-2 for Ni upon the introduction of Schottky gate metal. Through the analysis of the depletion of 2DEG, which is attributed to both Schottky junction and the lowered energy of Schottky barrier height, it was concluded that the diminished sheet carrier density of 2DEG originated from the reduction of surface donor state induced by gate metal.
- Publication:
-
Applied Physics Letters
- Pub Date:
- March 2012
- DOI:
- 10.1063/1.3695056
- Bibcode:
- 2012ApPhL.100k1908H
- Keywords:
-
- aluminium compounds;
- electron density;
- electroreflectance;
- gallium compounds;
- gold;
- III-V semiconductors;
- nickel;
- Schottky barriers;
- semiconductor heterojunctions;
- semiconductor-metal boundaries;
- surface states;
- two-dimensional electron gas;
- wide band gap semiconductors;
- 73.40.Kp;
- 73.40.Ns;
- 78.20.Jq;
- 73.30.+y;
- 73.20.At;
- III-V semiconductor-to-semiconductor contacts p-n junctions and heterojunctions;
- Metal-nonmetal contacts;
- Electrooptical effects;
- Surface double layers Schottky barriers and work functions;
- Surface states band structure electron density of states