Microwave surface transport in narrow-bandgap PdSe2 -MOSFETs

Abstract Group-10 transition-metal dichalcogenides are puckered van der Waals semiconductors, with a narrow bandgap, envisioned for ultra-broadband infrared (IR) detection. To assess their dynamical transport properties we investigate P d S e 2 n-MOSFETs by using microwave admittance spectroscopy. We report on surface channel inversion-depletion-accumulation behaviors with a depletion length of 15 n m , a mobility of 110 c m 2 V − 1 s − 1 , and a bulk bandgap of 0.15 e V . Our 10 µ m long devices have an electronic cut-off frequency in the GHz range promising a large gain-bandwidth product, competitive with that of III–V (InAs) and II–VI (HgCdTe) devices. The integration of bulk absorption and surface readout in P d S e 2 -MOSFETs is a monolithic geometry suitable for fast IR detection in the application-rich 1– 10 μ m range, which includes molecular spectroscopy, atmospheric communications and thermal sensing.