Due to dopant migration, build-in electric field exists in the device.There is open-circuit photoresponse, the detector can operate in photovoltaic mode.

元件受掺杂迁迁响而存在内建电场，使得元件有路响应，存在光致电压模式。

Base on this structure, the photoresponse of each spectral shape is tunable by the period of gratings.

我们用各种不同周期光栅结构来调变响应波形。