Demonstration of Al<i>X</i>Ga1-<i>X</i>N Solar-Blind UV Phototransistor With Double Heterostructures and Winding Gate

Abstract

<p>We have demonstrated a solar-blind ultraviolet (UV) phototransistor (PT) equipped with AlyGa 1−y N/AlxGa 1−x N/AlzGa 1−z N double heterostructures and winding gate configuration. There exists a 2-D electron gas (2DEG) at Al 0.55 Ga 0.45 N/Al 0.4 Ga 0.6 N heterointerface, due to the intrinsic polarization effect of AlxGa 1−x N. The Ni/Au metal stacks are deposited between two-sided interdigital Ohmic electrodes to form a Schottky gate. The gate can act as a switch to close or open the conduction channel between source and drain by the regulation of the 2DEG density. Thus, when given a specific negative gate voltage, the fabricated PT exhibits a photocurrent-to-dark-current ratio (PDCR) of 2.24×103 and a high responsivity of 1.86×103 A/W under 280 nm UV illumination at Vds=2 V, a high specific detectivity of 5.84×1014 Jones included, implying outstanding ability to detect solar-blind UV. Besides, to grasp the underlying mechanism of gate control and double heterostructures, comprehensive 2-D device simulations have performed, revealing that the variation trends of energy band and electron concentration are affected by the applied negative gate bias and incident light.<br></p>