Fast and Broadband Photoresponse of a Few-Layer GeSe Field-Effect Transistor with Direct Band Gaps

Abstract

Few-to-monolayer germanium selenide, a new IV–VI group layered material recently fabricated by mechanical exfoliation and subsequent laser thinning, is promising in very fast and broadband optoelectronic applications for its excellent stability, complicated band structures, inert surface properties, and being a natural p-type semiconductor. However, large-scale production of such few-layer GeSe devices with superior performance is still in early stages. In this study, field-effect transistors made of few-layer GeSe with direct band gaps are fabricated. Transistor performance with Schottky contact characteristics is measured at room temperature. A field-effect mobility of 4 cm2/(V s) and drain currents modulated both by holes and electrons are measured. Photoresponses as a function of illumination wavelength, power, and frequency are characterized. The few-layer GeSe transistor shows photoresponse to the illumination wavelengths from visible up to 1400 nm and a photoresponse rise (fall) time of 13 μs (19 μs), demonstrating very broadband and fast detection. The ambipolar behavior and the photoresponse characteristics demonstrate great potential of few-layer GeSe for applications in highly stable, very fast, and very broadband optoelectronic devices.

Enhanced Photoresponse in GeSe‐Based Phototransistors by Ferroelectric Gating

“…As such, the height of the Schottky barrier between GeSe and the metallic electrodes will increase, and the generated photocurrent will be further suppressed. [16,20,39] Finally, the EQEs of both devices are calculated by measuring the photocurrent at different wavelengths. EQE describes the ratio of the number of outgoing free electrons to that of the impinging photons.…”

“…[15] Zhao suggested a bottom-gate GeSe-based transistor which can respond to the illumination wavelengths from the visible light to 1400 nm with a fast response speed. [16] Improving the photoresponsivity is one of the most important issues in developing high-performance photodetectors. The photoresponsivity of 2D-semiconductor-based phototransistors can be tuned by the channel material, [17,18] gate electric field, [19] and operating temperature.…”

Ultra‐Thin GeSe/WS2 Vertical Heterojunction with Excellent Optoelectronic Performances

“…[23] 2D WS 2 has shown extremely high photoelectric absorption coefficient and quantum conversion efficiency, [24] which is especially excellent in the application of optoelectronics. On the other hand, as the most representative semiconductor in IV-VI group, GeSe has attracted increasing attention because of its excellent characteristics, including complicated band gaps, [25] broadband photoresponse (400-1400 nm), [26]…”

“…Constructing heterostructures with excellent performances takes comprehensive advantage of their electronics. Encouraged by the successful isolation of various 2D materials, designed heterostructures made by transferring one layered 2D material onto another and bonding through van der Waals (vdW) interactions for monolayer GeSe), [27] fast photoresponse time (10-20 µs), [26] high stability, surface inertness, and environmental friendliness, and so on.…”

2D Layered Material Alloys: Synthesis and Application in Electronic and Optoelectronic Devices

“…[ 52 ] In particular, a remarkable photoelectric power conversion efficiency of up to 23.4% can be achieved based on the optimally designed heterostructure. It is noteworthy that a number of 2DLMs share a common stoichiometric formula (e.g., MX, [ 53 , 54 , 55 , 56 , 57 , 58 , 59 ] MX 2 , [ 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] MX 3 , [ 71 , 72 , 73 , 74 ] M 2 X 3 , [ 75 , 76 , 77 , 78 , 79 , 80 ] ABX 2 , [ 81 , 82 ] ABX 3 , [ 35 , 83 , 84 , 85 ] etc.) and analogous crystal structures.…”