短周期Ⅱ型InAs/GaSb超晶格中红外探测

Short-period InAs/GaSb type-II Superlattices for Mid-infrared Detection

文章研究了短周期InAs/GaSb(SLs)Ⅱ型超晶格的红外光电特性。研究发现将InAs/GaSb超晶格各层生长宽度调节在20/25左右,可以实现中红外波段的禁带宽度。我们发展了修正的八能带K.P模型计算了该超晶格系统的电子子带结构,模型充分考虑了生长层之间的界面效应。模型只需要微观界面效应这一个可调参数,就可以得到与实验结果符合的非常好的理论结果。研究发现将GaSb的厚度固定为24,InAs的厚度从23降到17时,SLs的带隙宽度可以从275 meV调节到346 meV;或者InAs的厚度为21,GaSb的厚度从18增加到27时,SLs的带隙宽度可以从254meV调至313meV。该理论研究证明短周期InAs/GaSbⅡ型SLs可以应用于带宽为3~5μm的中红外光电探测。

We presented a theoretical study on optoelectronic properties of short-period InAs/GaSb type-Ⅱsuperlattices（SLs）grown along the[001]direction.The InAs/GaSb layer widths were varied around 20/25to achieve a variety of mid-infrared band gaps.The electronic mini-band structure for such SLs is calculated by the modified eight-band K·P model that incorporates the microscopic interface effect.With only one adjustable parameter characterizing the microscopic interface effect,we can achieve a good agreement between theoretical results and experimental data.Varying the SL layer thickness,we are able to change the SL band gap from 275 to 346 meV by decreasing the InAs layer thickness from 23to 17at a fixed GaSb layer thickness of 24,or from 254 to 313 meV by increasing the GaSb layer thickness from18to 27at a fixed InAs layer thickness of 21.This study confirms further that short-period InAs/GaSb type-II SLs can be used as mid-infrared photodetectors working at the 3~5μm bandwidth.