Large-Area GeSe Realized Using Pulsed Laser Deposition for Ultralow-Noise and Ultrafast Broadband Phototransistors

Here, we report on the comprehensive growth, characterization,and optoelectronic application of large-area, two-dimensional germaniumselenide (GeSe) layers prepared using the pulsed laser deposition(PLD) technique. Back-gated phototransistors based on few-layered2D GeSe have been fabricated on a SiO2/Si substrate forultrafast, low noise, and broadband light detection, showing spectralfunctionalities over a broad wavelength range of 0.4-1.5 mu m.The broadband detection capabilities of the device have been attributedto the self-assembled GeO x /GeSe heterostructureand sub-bandgap absorption in GeSe. Besides a high photoresponsivityof 25 AW(-1), the GeSe phototransistor displayed ahigh external quantum efficiency of the order of 6.14 x 10(3)%, a maximum specific detectivity of 4.16 x 10(10) Jones, and an ultralow noise equivalent power of 0.09 pW/Hz(1/2). The detector has an ultrafast response/recovery time of3.2/14.9 mu s and can show photoresponse up to a high cut-offfrequency of 150 kHz. These promising device parameters exhibitedby PLD-grown GeSe layers-based detectors make it a favorable choiceagainst present-day mainstream van der Waals semiconductors with limitedscalability and optoelectronic compatibility in the visible-to-infraredspectral range.

Automated summary

This study presents the growth, characterization, and optoelectronic application of large-area, 2D germanium selenide (GeSe) layers using pulsed laser deposition (PLD). Phototransistors based on few-layered 2D GeSe on a SiO2/Si substrate were fabricated for ultrafast, low noise, and broadband light detection. The GeSe phototransistor exhibited high photoresponsivity, external quantum efficiency, specific detectivity, and ultralow noise equivalent power, with an ultrafast response time and photoresponse up to a high cut-off frequency. These promising features make PLD-grown GeSe layers a favorable choice for optoelectronic devices in the visible-to-infrared spectral range.