n型Al_xGa_(1-x)N材料的电学和光学性质

Electrical and Optical Properties of n-type Al_xGa_(1-x)N

文章介绍了无裂纹高导电性n型A lxGa1-xN的MOCVD生长及其电学、光学和表面形貌性质。通过A lN两步生长法,有效地解决了A lxGa1-xN外延薄膜易裂的难题。并且对其生长进行优化,减少了A lxGa1-xN外延薄膜中的受主补偿缺陷,从而实现了高导电性的n型A lxGa1-xN薄膜,其载流子浓度为4.533×1018cm-3,并且电子迁移率高达77.5cm2/V.s,已经达到了目前国际上报道的先进水平。另外光学吸收谱说明A lxGa1-xN外延薄膜在302nm处具有陡峭的带边吸收,同时结合原子力显微镜分析材料的表面形貌,证实了材料表面光滑且平整。

Highly-conductive and crack-free Si-doped AlxGa1-xN alloys with x = 0.315 were grown by metal organic chemical vapor deposition （MOCVD） using low-temperature AlN nucleation. By optimizing two-steps growth of AlN buffer layer, room-temperature Hall measurements showed the high electron concentration of 4. 533 × 10^18cm^- 3 with mobility of 77.5cm^2/V· s. Thus, a resistivity value of 0. 01779Ω· cm had been achieved for Al0.315Ga0.685N. The optical properties of Al0.3,5 Ga0.685 N. epilayers were extensively investigated by optical absorption measurements. A very sharp absorption cutoff wavelength was obtained at 302nm and several Fabry-Perot interference peaks were apparently observed above 302nm due to extraordinary smoothness of AlxGa1-xN epilayers. This was also confirmed by atomic force morphology.