光柵結構之設計與製作以利超晶格紅外線偵測器耦合垂直入射光

Abstract

我們所設計紅外線偵測器的偵測波段是在６∼１２μm。由於電子躍遷的選擇律之限制，超晶格紅外線偵測器僅能吸收電場分量垂直於量子井層的入射光。明顯地，這個條件限制了偵測器陣列之製作。然而在熱影像的應用中，二維偵測器陣列的耦合是必要的。所以我們在超晶格紅外線偵測器上製作了光柵結構，垂直入射的光經過了光柵結構產生了繞射而耦合到偵測器中。 我們製作了三種不同週期的光柵結構，而光線由正面入射。我們可以利用各種不同週期的光柵結構來調變響應的波形。這是因為響應的波形會受到表面電漿共振的影響。而表面電漿共振的頻率可以用光柵的週期來控制。在本篇論文中，我們成功地利用光柵結構製作出可以正向入射的紅外線偵測器，而且響應的波形可以利用表面電將共振來調變。

The superlattice infrared photodetector (SLIP) is designed for wavelength 6~12μm detection. Due to the selection rule of electron transition, only the light polarized in the growth direction can cause intersubband transition. Clearly, this illumination scheme limits the configuration of detectors to linear arrays and single arrays of these detectors. Therefore, the grating structure can be fabricated on the SLIP to couple normal incident light. The incident light is coupled by the diffraction effect on the grating structure. We fabricate three devices with different period of gratings for topside-illumination. Base on this structure, the photoresponse of each spectral shape is tunable by the period of gratings. The response shape is affected by surface plasmon. The plasmon peak can be selected by period of gratings. In summary, the experimental results confirm the applicability of SLIPs with grating structure for coupling the normal incident light and tunable response shape by surface plasmon.