Role of Ga Vacancy on a Multilayer GaTe Phototransistor

Abstract

We report a high-performance field-effect transistor (FET) and phototransistor based on back-gated multilayer GaTe nanosheets. Through both electrical transport measurements at variable temperatures and first-principles calculations, we find Ga ion vacancy is the critical factor that causes high off-state current, low on/off ratio, and large hysteresis of GaTe FET at room temperature. By suppressing thermally activated Ga vacancy defects at liquid nitrogen temperature, a GaTe nanosheet FET with on/off ratio of ∼10(5), off-state current of ∼10(-12) A, and negligible gate hysteresis is successfully demonstrated. Furthermore, a GaTe phototransistor with high photogain above 2000 and high responsivity over 800 AW(-1) is achieved, as well. Our findings are of scientific importance to understand the physical nature of intrinsic GaTe transistor performance degradation and also technical significance to unlock the hurdle for practical applications of GaTe transistors in the future.

Highly Anisotropic GeSe Nanosheets for Phototransistors with Ultrahigh Photoresponsivity

“…The optimized photoresponsivity can reach 1.6 × 10 5 A W −1 (under illumination of 532 nm light), which is about five orders of magnitude higher than those of previously reported GeSe‐based photodetectors13, 22 and 100 times higher than that of monolayer MoS 2 23. As far as we know, this is better than most reported responsivities of similarly structured phototransistors based on single pristine 2D materials13, 22, 23, 24, 25, 26, 27, 28 without further hybridization and functionalization. The high responsivity can be attributed to the highly efficient light absorption as well as the enhanced photoconductive gain resulting from the existence of trap states.…”

“…As far as we know, this is better than most reported responsivities of similarly structured phototransistors based on single pristine 2D materials28, 54 without further hybridization and functionalization. The comparison of photodetectors based on different 2D materials is summarized in Table 1 13, 22, 23, 24, 25, 26, 27, 28. The intrinsic responsivity R 0 and the photoconductive gain G both contribute to the total responsivity:55 $R_{\lambda }\hspace{0.17em}\mathrm{=}\hspace{0.17em}\hspace{0.17em}{R}_0\cdot G\hspace{0.17em}\mathrm{=}\hspace{0.17em}\hspace{0.17em}\frac{\eta \mathrm{e}}{hv}\cdot G$, where η is the quantum efficiency and υ is the frequency of incident light.…”

Crystal quality of two-dimensional gallium telluride and gallium selenide using Raman fingerprint

“…27 Thermally activated Ga vacancy defects in multilayer GaTe has been reported in field effect transistor (FET) and phototransistor application. 28 The thicknesses dependent PL of GaTe and GaSe films has also been reported, where in both materials, PL shows a dramatic decrease of intensity at a reduced film thickness due to non-radiative carrier escape via surface states. Thus, the need for surface passivation of the GaTe and GaSe films has also been emphasized.…”

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…and group III–VI nanomaterials (InSe,38, 39, 40, 41, 42 GaSe,43, 44, 45, 46, 47, 48 etc.) have been extensively investigated in many fields including photodetectors,49, 50, 51, 52, 53, 54, 55, 56, 57, 58 gas sensors,59, 60 field effect transistors (FETs),38, 61, 62, 63, 64, 65 and flexible devices 66, 67, 68…”