分子束外延PbTe薄膜中的红外光电导探测器

中红外探测器在诸多领域具有重要的应用,目前,我国在PbTe、PbSe中红外探测器方面研制较少,通过分子束外延技术、以CdZnTe(lll)为衬底生长PbTe外延薄膜,XRD表征表明:PbTe外延薄膜是单晶薄膜,且与衬底具有相同(lll)取向,光吸收光谱测量得到外延薄膜的光学吸收边位于3.875 μm,光致发光谱显示发光波长位于3.66 μm,蓝移是红外激光泵浦导致PbTe温升所致.以PbTe为有源区材料、ZnS薄膜作为钝化和绝缘材料,用AuPtTi合金作为欧姆接触电极,研制了PbTe光电导中红外探测器原型器件,探测器在78 K温度下的光电导响应在红外波段的1.5～5.5μm,探测率约为2×10~9 cm·Hz~(1/2)·W~(-1).最后,对影响探测器工作的因素和改进方法进行了讨论.

PbTe thin film mid-infrared photoconductive detectors grown by molecular beam epitaxy

Mid-infrared detectors have important applications in many fields.Due to the lack of PbTe and PbSe mid-infrared detectors in China,PbTe thin films on CdZnTe(lll)substrates had been epitaxially grown by using molecular beam epitaxy.XRD characterization showed that the PbTe epitaxial films displayed the single crystalline quality with(lll)orienmtion.Optical absorption spectrum measured an optical absorption band edge at 3.875μm,and its photoluminescence showed a luminescence peak at 3.66μm.The blue shift of the PL peak was attributed to the rise of PbTe temperature by laser excitation.The prototype photoconductive mid-infrared detectors was fabricated by using PbTe epilayers as the active regions.ZnS thin films as the passivation and insulation material,AuPtTi thin films as the Ohm contact electrodes for PbTe.It had been found that these detectors had photoconductive response in the mid-infrared region of 1.5-5.5μm at 78K,and the detectivity was estimated to be higher than 2×10~9 cm·Hz~(1/2)·W~(-1).Various factors affecting the performance of these detectors had also been discussed,as well as improved methods.