Publication Date:
2016-11-29
Description:
Unintentionally doped (UID) AlGaN epilayers graded over Al compositions of 80%–90% and 80%–100% were grown by metal organic vapor phase epitaxy and were electrically characterized using contactless sheet resistance ( R sh ) and capacitance-voltage ( C–V ) measurements. Strong electrical conductivity in the UID graded AlGaN epilayers resulted from polarization-induced doping and was verified by the low resistivity of 0.04 Ω cm for the AlGaN epilayer graded over 80%–100% Al mole fraction. A free electron concentration ( n ) of 4.8 × 10 17 cm −3 was measured by C–V for Al compositions of 80%–100%. Average electron mobility ( μ ¯ ) was calculated from R sh and n data for three ranges of Al composition grading, and it was found that UID AlGaN graded from 88%–96% had μ ¯ = 509 cm 2 /V s. The combination of very large band gap energy, high μ ¯ , and high n for UID graded AlGaN epilayers make them attractive as a building block for high voltage power electronic devices such as Schottky diodes and field effect transistors.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
