PHOTONCOUNTING IN INFRA-RED REGION WITH SUPERLATTICE AVALANCHE PHOTODIODES

本研究的目的是研究InAlGaAs/InAlAs超晶格雪崩光电二极管（SLAPD）作为红外区域光子计数方法的超低光探测器件的特性性能。研究结果主要总结如下：1)采用液氮冷却系统冷却SLAPD，工作温度为85 k。2)在低偏置电压条件下，薄层SLAPD的暗电流噪声明显降低，噪声的主要成分是热激发载流子。在冷却作用下，SLAPD的击穿电压逐渐降低。3)在击穿电压附近，厚层SLAPD的暗电流噪声依次降至10-11 A，而薄层SLAPD的暗电流噪声依次降至10-9 A。这种噪音被认为是隧穿的暗电流。结果表明，超晶格倍增层可以有效地控制多余的噪声系数，加厚层也可以有效地抑制隧穿暗电流。该SLAPD可用于10-6 W ~ 10-12 W的光功率。4)尝试使用厚层SLAPD进行光子计数，但信号的脉冲高度分布在光信号脉冲和噪声脉冲之间没有明显的差异。微等离子体产生的暗电流噪声仍然存在。这些结果表明，具有较厚超晶格层的slapd具有在红外区域用作光子计数器件的潜力。这种装置的设计和制造技术的发展是迫切需要的。

The purpose of this research is to investigate the characteristic performance of an InAlGaAs/InAlAs superlattice avalanche photodiode (SLAPD) as an ultra-low light detecting device for photoncounting method in infra-red region. The results are mainly summarized as follows.1) The SLAPD's were cooled by a liquid-nitrogen cooling system and operated at 85 K.2) As the decrease of the dark current noise of the thin-layr SLAPD was remarkably seen in the low bias voltage condition, the main component of the noise was caused from the thermally excited carriers. The breakdown voltage of the SLAPD moved to lower one by the cooling. 3) Dark current noise of the thick-layr SLAPD was successively reduced to 10-11 A at around the breakdown voltage, on the other hand that of the thin-layr SLAPD was 10-9 A.The noise was supposed the tunneling dark current. It was shown that the superlattice multiplication layr was effective to control the excess noise coefficient and the thickened layr was also effective to suppress the tunneling dark current. This SLAPD could be used in optical power of 10-6 W to 10-12 W.4)Photoncounting by using the thick-layr SLAPD was tried, but the pulse height distribution of the signal did not show a clear difference between the light signal pulse and the noise pulse. The dark current noise caused from the microplasma was still left.These results shows that the SLAPDs with the thicker superlattice layr have a potential for the photoncounting device in infra-red region. The development of the design and fabrication technique for such devices is strongly requested.