Solar-blind ultraviolet photodetectors based on superlattices of AlN/AlGa(In)N

Abstract

We describe solar-blind photodetectors based on superlattices of AlN/AlGa(In)N. The superlattices have a period of 1.4 nm, determined by x-ray diffraction, and an effective band gap of 260 nm measured by optical reflectivity. Using simple mesa diodes, without surface passivation, we obtain low dark leakage currents of 0.2–0.3 pA, corresponding to the leakage current density of ∼0.3 nA/cm2, and high zero-bias resistance of ∼1×1011 Ω. Excellent visible cutoff is obtained for these devices, with six orders of magnitude decrease in responsivity from 260 to 380 nm. These results demonstrate the potential of junctions formed by short-period superlattices in large-band-gap devices.

Ultraviolet optoelectronic devices based on AIGaN alloys grown by molecular beam epitaxy

“…As shown in Figure 21, the AlGaN-based material system is well suited for UV photodetectors because its direct band gap can be tuned from 360 to 200 nm by changing the alloy composition, enabling true visible-blind or solar-blind detectors. [21][22][23][24][25][26][27][28][29] Excellent reviews on UV photodetectors were presented in Refs 23, 26.…”

“…The values of the photoconductive gain and responsivity of AlGaN UV detectors, reported by various groups, were found to vary widely. [21][22][23][24][25][26][27][28][29] To find the origin of this variation, we fabricated a number of UV photoconductive detectors from GaN of varying resistivity and AlGaN of various compositions and determined the (μτ) product from the gain measurements. [25,28,138] Figure 22 shows the (μτ) product for the fabricated GaN and AlGaN photoconductive detectors.…”

“…[20] Significant progress has been made in AlGaN-based "visible blind" or "solar blind" UV detectors to detect weak UV signals in the presence of strong ambient light in scientific research, industrial, and military applications. [21][22][23][24][25][26][27][28][29] UV electroabsorption modulators have generally received much less attention. [30][31][32][33][34][35][36] In this paper, we review progress in developing UV optoelectronic devices based on AlGaN alloys grown by plasmaassisted molecular beam epitaxy (PAMBE).…”

High responsivity in molecular beam epitaxy grown β-Ga2O3 metal semiconductor metal solar blind deep-UV photodetector

“…6 Fig . 5 illustrates the plot of the responsivity versus dark current for the state-of-the-art solar blind (230-290 nm) UV detectors reported [4][5][6]8,[10][11]16,[30][31][32][33][34][35][36][37] for the devices based on Al x Ga 1-x N as well as on β-Ga 2 O 3 . The detectors reported in this work have excellent responsivity while maintaining a very low dark current for 230-240 nm range.…”

β-Ga2O3 solar-blind deep-ultraviolet photodetector based on a four-terminal structure with or without Zener diodes

“…1,2 In this case, photodetectors based on wide-bandgap semiconductors are regarded as better alternatives. Among them, monoclinic Ga 2 O 3 ( β-Ga 2 O 3 ) with an intrinsic E g of 4.9 eV is naturally suitable for solar-blind DUV detection, 9,10 and so can avoid the alloying process in material growth for AlGaN 11,12 and ZnMgO. 13 As a result, β-Ga 2 O 3 has attracted much attention in recent years, and its characteristics of solar-blind DUV detection have been demonstrated in various device structures.…”