非掺杂n型氮化镓外延层的光致发光

研究了热处理对非掺杂n型氮化镓外延层光致发光谱的影响和光谱中各发光带强度与温度之间的关系．热处理后，光谱中的带边峰和黄光峰的强度较热处理前都有明显降低．黄光峰强度随温度升高的衰减速度要比带边峰慢得多．由这些实验结果得出结论：光谱中的带边峰是由自由激子和束缚在一浅施主能级的束缚激子的谱线重合而成，这个浅施主能级很有可能是由氮空位产生；黄色荧光的机制应为自由电子或施主能级向深受主能级的跃迁，并且黄色荧光肯定和氮化镓中的一内部缺陷产生的深受主能级有关，该内部缺陷很有可能是镓空位．

Photoluminescence of Undoped n-Type GaN Epilayer

The influence of annealing on the photoluminescence of the undoped n-type GaN epilayer as　well　as the relations　between　the　temperature　and the intensity of every emission band in the photoluminescence spectra have been investigated.After annealing,the intensity of both　the edge peak and the yellow peak decreases obviously compared with that before annealing;the attenuation degree of the edge peaks intensity after annealing reduces with the temperature increasing at a higher decay rate than that of the yellow peak.According to these results,it is concluded that the edge peak in the spectra is a overlap of the free exciton and the shallow-donor-bound exciton spectra．The shallow donor level is likely generated due to the VN.The mechanism of the yellow luminescence is the transition of the conduction band or donor levels to the deep acceptor levels,while the yellow luminescence surely correlates with the deep acceptor states that are generated due to an intrinsic defect,possibly VGa,in the GaN.