不同含氮量的a-Si:H/a-SiNx:H超晶格界面性质的研究

通过电调制吸收、光热偏转谱、光致发光及红外吸收谱等实验技术,研究了不同含氮量的a-Si:H/a-SiN_x:H超晶格的界面性质。由电调制吸收测试得出的界面电荷密度Q_s～10¹²cm^-2。Q_s比由光热偏转谱所获得的界面态密度N_i～10¹¹cm^-2大出约半个数量级。N_i,Q_s,及光致发光相对峰值 关键词：

THE EFFECTS OF NITROGEN CONTENT OF a-SiNx:H ON THE INTERFACE PROPERTIES IN a-Si:H/a-SiNx:H SUPERLATTICES

The effects of nitrogen content on the interfacial properties in a-Si:H/a-SiN_x:H superlat-tices have been studies by electroabsorption (EA) photothermal deflection spectroscopy (PDS), photoluminescence (PL) and infrared (IR). The density of interface charges Q_s deduced from EA is approximately 10¹²cm^-2. The density of interface states Ni estimated by PDS is ～10¹¹cm^-2 which is smaller by a factor of 5 than Q_s. The nitrogen content x dependences of Q_s, N_i and the relative peak intensity of luminescence I_pl exhibit similar behavior and show extreme values at x=x_c which is defined as critical value of nitrigen content. The critical values of nitrogen content are in the x range of 0.85-0.95. The measurements of IR reveal that the absorption of N-H bonds increases rapidly with increasing x in the range of 0.6-1.0. The asymmetry of interfaces and a possible mechanism of presence of critical values are discussed-For interpretating the phenomena observed, a model of charged nitrogen dangling bond is suggested.