High-sensitivity mid infrared detection using photoionization of quantum dots

我们设计并制造了一个量子点红外光电探测器，它利用了量子点的光电离和随后在调制掺杂的AlGaAs/GaAs二维通道中光激发载流子的横向输运。由于自组装InAs量子点的结合-连续子带间吸收，在中红外范围内观察到宽的光电流信号。在调制掺杂的传导通道中，光激发载流子的长寿命和高迁移率实现了非常高的响应率（-5 A/W）。为了实现高灵敏度的光探测，我们还利用InAs量子点实现了中红外光子计数器。为了实现这一目标，我们利用金属纳米间隙电极制作了横向单电子隧道结构，并成功地观察到在4.2 K下明显的库仑封锁和壳结构样电导变化。

We have designed and fabricated a quantum dot infrared photodetector which utilizes photoionization of quantum dots (QDs) and subsequent lateral transport of photoexcited carriers in the modulation-doped AlGaAs/GaAs two-dimensional channels. A broad photocurrent signal has been observed in the mid infrared range due to the bound-to-continuum intersubband absorption in the self-assembled InAs QDs. A very high responsivity (-5 A/W) has been realized by a long lifetime of photoexcited carriers as well as high mobility in the modulation-doped conduction channels.Towards the ultimate sensitivity photodetection, we have also made an effort to realize mid infrared photon counters by using InAs QDs. Toward this goal, we fabricated lateral single electron tunneling structures by using metallic nanogap electrodes and successfully observed a clear Coulomb blockade and a shell structure-like conductance change at 4.2 K.