非晶态碲化汞薄膜的光电特性研究

摘要

The amorphous HgTe films were prepared by the RF magnetron sputtering technique onto quartz substrates. The source of light is a He-Ne Laser(hv=l.96 eV, λ=632.8 nm). The dark conductivity(σd),steady state photoconductivity(σp), and photosensitivity (σp/σd) of amorphous HgTe films were investigated in the range of 80～300 K temperatures. Both σd andσp of amorphous HgTe films are thermally activated in the 80～300 K temperature range. Two temperature regions have been observed in temperature dependence of dark conductivity of amorphous HgTe films: in the range of the low temperature (80 K≤ T≤ 180 K), σd is poorly activated with T (activation energy ～15 meV), and in the range of high temperature (180 K＜ T≤300 K), σd is strongly thermally activated with activation energies ～400meV. The measurement of σp as a function of T indicates the presence of three distinct regions: (1) For 80 K≤T≤180 K, σp is poorly activated with T (activation energy ～20meV), (2) for 180 K＜T≤280 K, σp is thermally｀activated with activation energies ～ 120meV, and (3) for T＞280 K, a thermal quenching(TQ) of σp is measured in all the amorphous HgTe films. A maximum in photoconductivity is observed at a particular temperature (～280 K) while the maximum of the photosensitivity is at ～ 180 K. Two conduction mechanisms were obtained in the amorphous HgTe films: conduction in the located states and conduction in the extended states. 180 K is the transform temperature of two conduction mechanisms. The results of the paper indicate that the amorphous HgTe films will be promising materials for many applications in infrared detectors operating at high temperature (～ 180 K).%利用射频磁控溅射方法在宝石衬底上制备了非晶态碲化汞(HgTe)薄膜材料,以He-Ne激光器(hv=1.96eV,λ=632.8nm)作为激励光源,在80～300K温度范围内,研究了非晶态HgTe薄膜的暗电导σd、稳态光电导σp以及光敏性σp/σd的特性,分析了载流子的导电和复合机制.实验发现,在80～300 K温度范围内,非晶态HgTe薄膜的暗电导和稳定态光电导均具有热激活特性.暗电导存在2个温区:在低温区(80K≤T≤180K),激活能约15meV;在高温区(180K≤T≤300K),激活能约400meV.穗定态光电导则存在明显的3个温区:(1)当80K≤T≤180K时,光电导具有弱的热激活特性(激活能约20meV);(2)当180K≤T≤280K时,光电导具有强烈的热激活特性(激活能约120meV);(3)当T＞280K时,光电导出现"热淬灭"效应.在温度约280K时,光电导具有最大值,而光敏性则在约180 K时具有最大值.非晶态HgTe薄膜中存在两种导电机制:定域态电导和扩展态电导,180 K两种导电机制的温度分界点.研究结果表明,非晶态HgTe薄膜很适合制备高工作温度(约180K)红外探测器.