High electron mobility in AlN:Si by point and extended defect management
Pegah Bagheri, Cristyan Quiñones-García, Dolar Khachariya, Shashwat Rathkanthiwar, Pramod Reddy, Ronny Kirste, Seiji Mita, James Tweedie, Ramón Collazo, Zlatko Sitar
Abstract
High room temperature n-type mobility, exceeding 300 cm2/Vs, was demonstrated in Si-doped AlN. Dislocations and CN−1 were identified as the main compensators for AlN grown on sapphire and AlN single crystalline substrates, respectively, limiting the lower doping limit and mobility. Once the dislocation density was reduced by the growth on AlN wafers, C-related compensation could be reduced by controlling the process supersaturation and Fermi level during growth. While the growth on sapphire substrates supported only high doping ([Si] > 5 × 1018 cm−3) and low mobility (∼20 cm2/Vs), growth on AlN with proper compensation management enabled controlled doping at two orders of magnitude lower dopant concentrations. This work is of crucial technological importance because it enables the growth of drift layers for AlN-based power devices.