PHOTONCOUNTING IN INFRA-RED REGION WITH SUPERLATTICE AVALANCHE PHOTODIODES

本研究的目的是探讨InAlGaAs/InAlAs超晶格雪崩光电二极管（SLAPD）作为红外光子计数法的超低光探测器件的特性。实验结果表明：1）采用液氮冷却SLAPD，工作温度为85 K; 2）在低偏压条件下，SLAPD暗电流噪声显著降低，其主要成分是热激发载流子。SLAPD的击穿电压随着冷却温度的降低而降低。3)在击穿电压附近，厚层SLAPD的暗电流噪声逐渐减小到10 ~（-11）A，而薄层SLAPD的暗电流噪声为10 ~（-9）A，推测其为隧穿暗电流噪声。结果表明，超晶格倍增层对控制超噪声系数是有效的，增厚层对抑制隧穿暗电流也是有效的。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显示出明显的差异。这些结果表明，具有较厚超晶格层的SLAPD在红外光子计数器件方面具有潜力。这类器件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.