基於斷帶能隙n-n異質結構之三硫族化合物的負差分電阻

Abstract

二維半導體異質結構在光電子學領域中為眾多令人興奮的現象鋪平了道路。其中，具有多個閾值的非線性電流-電壓特性在多值邏輯中找到了應用，可以增加電子器件的密度。這種載流子傳輸行為被稱為負差分電阻（NDR），其在能帶對能帶隧道效應的幫助下在能帶間斷的能帶對齊異質結構中實現。在這裡，我們展示了在室溫下第III型ZrS3/SnS2異質結構中的這種能帶間隧道效應。在室溫下測量的電流-電壓特性曲線中觀察到了明顯的NDR效應，其峰谷比（PVR）為1.7。通過製備具有不同幾何形狀和厚度的ZrS3器件，我們仔細研究了電極和2D材料之間界面處金屬誘導的能帶狀態對室溫下實現NDR效應的影響。結果表明，為了觀察到NDR效應，選擇適當的金屬電極非常重要。在雷射照射下，NDR效應更加顯著，並且在較低的閘極電位下觀察到。由於兩種材料中存在相當小的光學能隙，ZrS3/SnS2異質結構可作為光探測器。該器件的光響應度被估計為300 mA W-1，用於非常低功率的激光，並且檢測性能的數量級為10^10 Jones。因此，所提出的ZrS3/SnS2異質結構展示出顯著的NDR效應和合理的光響應度，在近期的奈米電子學領域具有廣泛的應用前景。

Two-dimensional (2D) semiconductor heterojunction has paved the way for numerous exciting phenomena in the field of optoelectronics. Among them, a non-linear current-voltage behavior with multiple threshold values finds its application in multi-valued logic, which can increase the device density in electronics. This carrier transport behavior termed negative differential resistance (NDR) is aided by band-to-band tunneling in the broken-gap energy band-aligned heterostructures. Here, we demonstrate this interband tunneling effect in type-III ZrS3/SnS2 heterostructure at room temperature. A prominent NDR effect with a peak-to-valley ratio (PVR) of 1.7 was observed in the current-voltage characteristic curves measured at room temperature. The effect of the metal-induced gap states at the interface between electrode and 2D material in the realization of the NDR effect at room temperature has been meticulously studied by fabricating ZrS3 devices with different geometry and thickness. The results indicate that in order to observe NDR effect, the choice of a suitable metal electrode is very important. Under the illumination of a laser, the effect of NDR becomes more pronounced and observed at lower gate potential. The ZrS3/SnS2 heterostructure works as a photodetector due to a considerable optical band gap in both materials. The photoresponsivity of the device was estimated to be 300 mA W-1 for a very low laser power and the detectivity was determined to be in the order of 1010 Jones. Hence, the proposed ZrS3/SnS2 heterostructure exhibiting a significant NDR effect and reasonable photoresponsivity has a wide scope in the field of nanoelectronics in the near future.