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针对缓变结和突变结,计算了碲锡铅扩散结光生伏特探测器在零偏压时的电阻——面积之乘积R_oA。对抗缓变结而言,提出的公式论证了少数载流子扩散电流,耗尽层电流以及隧道电流被加以考虑时,R_oA 与梯度常数的全部依赖关系,对抗突交结,同样也针对扩散、耗尽和隧道三种机理,画出了R_oA 与轻掺杂区载流子浓度的依赖关系。计算是按照两种有实际意义的器件来进行的:即扩散Sb 的Pb_(0.982)—Sn_(0.018)Te 在170°K 工作、截止波长为5微米和扩散Cd 的Pb_(0.79)Sn_(0.21)Te 在77°K 工作,截止波长为11微米。Sb 扩散结遵从缓变结模式,而在未退火的基片上作成的Cd扩散结是突变结。我们把计算值和测出的R_oA 之乘积加以比较,确定了这两类器件耗尽层中的近似寿命值。根据这些结果,画出了受热噪声限制的探测器的探测率D~*与R_oA 之关系曲线。能够证明:欲获得D~*的上限值,碲锡铅固有的短寿命起主导作用。
For the slow junction and the sudden junction, the product of resistance-area R_oA of the tellurium-tin-lead-diffused junction photovoltaic detector at zero bias is calculated. In terms of the resistance to slowing transitions, the proposed formula argues that when minority carrier diffusion current, depletion layer current and tunnel current are taken into consideration, R_oA depends on the gradient constant, Do and tunnel three kinds of mechanisms, draw the R_oA and lightly doped region carrier concentration dependence. The calculation is based on two practical devices: Pb_ (0.982) -Sn_ (0.018) Te for diffusion of Sb at 170 ° K with a cutoff wavelength of 5 μm and Pb_ (0.79) Sn_ (0.21 ) Te operates at 77 ° K with a cut-off wavelength of 11 microns. The Sb diffusion junction follows the slow junction mode whereas the Cd diffusion junction formed on the unannealed substrate is a mutant junction. We compare the product of the calculated value with the measured R_oA to determine the approximate lifetime values in the depletion layer of both types of devices. Based on these results, the relationship between the detection rates D ~ * and R_oA of the detector limited by the thermal noise is plotted. It can be demonstrated that the inherent short lifetime of tellurium-tin-lead plays a leading role in obtaining the upper limit of D ~ *.