Correlation between mobility collapse and carbon impurities in Si-doped GaN grown by low pressure metalorganic chemical vapor deposition
Abstract
In the low doping range below 1 × 1017 cm−3, carbon was identified as the main defect attributing to the sudden reduction of the electron mobility, the electron mobility collapse, in n-type GaN grown by low pressure metalorganic chemical vapor deposition. Secondary ion mass spectroscopy has been performed in conjunction with C concentration and the thermodynamic Ga supersaturation model. By controlling the ammonia flow rate, the input partial pressure of Ga precursor, and the diluent gas within the Ga supersaturation model, the C concentration in Si-doped GaN was controllable from 6 × 1019 cm−3 to values as low as 2 × 1015 cm−3. It was found that the electron mobility collapsed as a function of free carrier concentration, once the Si concentration closely approached the C concentration. Lowering the C concentration to the order of 1015 cm−3 by optimizing Ga supersaturation achieved controllable free carrier concentrations down to 5 × 1015 cm−3 with a peak electron mobility of 820 cm2/V s without observing the mobility collapse. The highest electron mobility of 1170 cm2/V s was obtained even in metalorganic vapor deposition-grown GaN on sapphire substrates by optimizing growth parameters in terms of Ga supersaturation to reduce the C concentration.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 08, 2016
- Source ID
- 10.1063/1.4962017
Entities
People
- Alexander Franke
- Andrew Klump
- Axel Hoffmann
- Felix Kaess
- Jingqiao Xie
- Luis H. Hernandez-balderrama
- Pramod Reddy
- Ramón Collazo
- Ronny Kirste
- Seiji Mita
- Shun Washiyama
- Zlatko Sitar
Organizations
- Army Research Office
- National Science Foundation
- North Carolina State University
- Technische Universität Berlin