Optimization of All Figure-of-Merits in Well-Aligned GaN Microwire Array Based Schottky UV Photodetectors by Si Doping

Abstract

GaN nano/microwires, due to their large surface-tovolume ratio and the reduced dimensionality, have been widely used in high-performance ultraviolet (UV) photodetectors (PDs). However, there has been a fundamental trade-off between the photocurrent gain and the speeds of PDs, which have limited their practical applications. In this work, highly ordered GaN microwire array based Schottky UV PDs have been fabricated, and optimizing Si doping concentrations can entirely improve the performances of the devices. The results show that output photocurrent increases monotonously as increasing doping concentration, while the dark current experiences a decrease followed by an increase, resulting in an optimized value under a certain doping concentration. At doping concentration of 1 × 10 18 cm −3 with 2.2 mW cm −2 illuminating intensity, the sensitivity, responsivity, and detectivity of the devices are greatly enhanced by 1.84 × 10 4 %, 163%, and 2103%, respectively. Meanwhile, the time-dependent response in Si-doped device possesses fast response time (τ on < 10 ms and τ off < 10 ms) at this optimum concentration, compared with that of undoped one (τ on = 70 ms and τ off = 90 ms). The effective advances in the devices are attributed to the increased Schottky barrier height by Si doping and the intensive oxygen molecules adsorption and desorption processes in microwire surface. This study offers a design guideline for the optimum doping concentration for obtaining high performances in microwire-based PDs.

Recent Progress of Heterojunction Ultraviolet Photodetectors: Materials, Integrations, and Applications

“…p‐Type SiC‐based photodetectors can achieve solar‐blind photodetection with fast speed and high signal‐to‐noise ratios 44. With a large direct bandgap of 3.4 eV, gallium nitride (GaN) is another outstanding material for visible‐blind UV detection because of its large light absorption coefficient, high saturation‐electron drift velocity (310 cm s −1 ), good thermal and chemical stability, and remarkable tolerability of harsh environments 45. The superior mechanical properties and chemical stability make SiC and GaN devices ideal UV photodetectors while working in harsh environments.…”

Aluminum Plasmonics Enriched Ultraviolet GaN Photodetector with Ultrahigh Responsivity, Detectivity, and Broad Bandwidth

“…GaN/Ag NPs 4 --- [15] GaN/Au NPs 11 -2.9 6.2 [39] Ni/GaN/Au 1.31 --- [43] Ni/GaN/Ti/Al 0.104 --- [44] GaN NWs 0.47 --- [42] GaN(p-i-n) 0.23 --- [41] GaN-Thin film 13.02 -0.21 1.2 [40] GaN micro Wire 450 2.08 × 10 11 0.07 0.09 [45] GaN array are shown in Figure 4d. The plotted photoresponsivity in the UV regime reveals a significant enhancement through the entire band, in contrast to that without the Al nanohole array, even up to unusual deep UV frequencies.…”

Enhanced Photoresponse Performance of Self‐Powered PTAA/GaN Microwire Heterojunction Ultraviolet Photodetector Based on Piezo‐Phototronic Effect

“…The growth procedure was described detailedly in the previous works of the group. [46,47,65] Device Fabrication: To fabricate the devices, Si wafers with the Si-doped GaN MWs were placed in the mixed acidic corrosive solution of HNO 3 , HF, and DI water (5:2:1) for 5 min, and the GaN MWs were stripped from the Si substrate, then the MWs were cleaned with DI water and put into isopropanol solution for storage. Then, using a plastic-tip dropper to draw the MWs from the isopropanol solution and dripped onto a quartz glass substrate for drying.…”