Single crystals of hybrid perovskites have shown remarkably improved physical properties compared to their polycrystalline film counterparts, underscoring their importance in the further development of advanced semiconductor devices. Here we present a new method of growing sizable CH3NH3PbCl3 single crystals based on the retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge recombination, and transport properties of CH3NH3PbCl3 single crystals. These crystals exhibit trap-state density, charge carrier concentration, mobility, and diffusion length comparable with the best quality crystals of methylammonium lead iodide or bromide perovskites reported so far. The high quality of the crystal along with its suitable optical band gap enabled us to build an efficient visible-blind UV-photodetector, demonstrating its potential in optoelectronic applications.

CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector.

Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date.

https://www.mdpi.com/1424-8220/10/9/8604/pdf

ZnO-Based Ultraviolet Photodetectors

Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

Low-dimensional (LD) nanostructures are ideal systems for constructing high-performance photodetectors due to their tailored geometries, high surface-area-to-volume ratios and rationally designed surfaces. This article provides a brief summary about recent progress on LD nanostructures based visible-light-blind ultraviolet photodetectors. The current challenges and an outlook on the future developments of this research field are summarized and highlighted.

Low-dimensional nanostructure ultraviolet photodetectors.

Due to its significant applications in many relevant fields, light detection in the solar-blind deep-ultraviolet (DUV) wavelength region is a subject of great interest for both scientific and industrial communities. The rapid advances in preparing high-quality ultrawide-bandgap (UWBG) semiconductors have enabled the realization of various high-performance DUV photodetectors (DUVPDs) with different geometries, which provide an avenue for circumventing numerous disadvantages in traditional DUV detectors. This article presents a comprehensive review of the applications of inorganic UWBG semiconductors for solar-blind DUV light detection in the past several decades. Different kinds of DUVPDs, which are based on varied UWBG semiconductors including Ga2O3, MgxZn1−xO, III-nitride compounds (AlxGa1−xN/AlN and BN), diamond, etc., and operate on different working principles, are introduced and discussed systematically. Some emerging techniques to optimize device performance are addressed as well. Finally, the existing techniques are summarized and future challenges are proposed in order to shed light on development in this critical research field.

Recent Progress in Solar-Blind Deep-Ultraviolet Photodetectors Based on Inorganic Ultrawide Bandgap Semiconductors

Epitaxial TiO2 thin films were fabricated on LaAlO3 single crystal substrates by RF magnetron sputtering. Ag electrodes were then evaporated on the TiO2 thin films to form metal–semiconductor–metal photoconductive detectors. The TiO2 photodetector exhibited a maximum photoresponse of 3.63 A W−1 at 310 nm with a sharp cutoff wavelength at 380 nm. The ultraviolet (UV)–visible response rejection ratio (R310 nm/R390 nm) was about three orders of magnitude. The photocurrent response of the detectors scaled linearly with the applied bias and the incident light intensity. The dark current was only 0.14 nA at 10 V bias. A transient photovoltage with a rise time of ~8 ns and a full-width at half-maximum of ~90 ns was observed when the photodetector was under the irradiation of a 308 nm XeCl laser with 25 ns duration. The excellent performances of high responsivity and ultrahigh response speed suggest that the presented TiO2 detectors have promising potential in UV photodetection.

https://iopscience.iop.org/article/10.1088/0022-3727/44/37/375104/pdf

Highly sensitive fast-response UV photodetectors based on epitaxial TiO2 films

Solar-blind deep-ultraviolet (DUV) photoconductive detectors based on an LaAlO3 (LAO) single crystal with interdigitated electrodes are reported. The LAO detectors show a high sensitivity to DUV light with wavelengths less than 210 nm, and the DUV/UV (200 versus 290 nm) contrast ratio is more than 2 orders of magnitude. The photocurrent responsivity of LAO detector reaches 71.8 mA/W at 200 nm at 10 V bias, and the corresponding quantum efficiency η is 44.6%. The noise current under sunlight at midday outdoors is only 77 pA. The experimental results indicate that the LAO detectors have attractive potential applications in DUV detection.

/pdf/solar-blind-deep-ultraviolet-photodetectors-based-on-an-2twe62x1yq.pdf

Solar-blind deep-ultraviolet photodetectors based on an LaAlO 3 single crystal

The photoelectric effects of LiTaO3 (LTO) single crystals are experimentally studied with two kinds of LTO wafers, 10° tilted and untilted, at room temperature. A transient open-circuit photoelectrical response of 143 ps rise time is observed in the 10° tilted LTO when a 266 nm pulsed laser with a duration of 25 ps is irradiated directly onto the LTO surface. The untilted LTO with interdigitated electrodes of 10 µm finger width and 10 µm interspacing exhibits a linear dependence on the applied bias and power density of incident light, a response peak at about 235 nm and a sharp cutoff at about 270 nm. The noise current is only 61 pA at 20 V bias under the illumination of sunlight outdoors at midday. The experimental results suggest the promising application of the LTO single crystal in UV detection, in particular, as a solar-blind fast-response photodetector.

/pdf/ultraviolet-fast-response-photoelectric-effects-in-litao-3-37dbfsrcll.pdf

Ultraviolet fast-response photoelectric effects in LiTaO 3 single crystal

We report high-sensitivity SrTiO(3) photoconductive detectors with multiple photoelectric cells connected in parallel The photocurrent of the detectors increases significantly with an increase of the cell number The photocurrent responsivity of the detector with three cells can reach 237 mA/W at 10 V bias under illumination of the 375 nm laser, and the corresponding quantum efficiency is 77% at 10 V bias Furthermore, a transient photovoltaic signal with a rise time of ~490 ps and a full width at half-maximum of ~900 ps is obtained These results demonstrate that the present devices with further improvement of performance have great potential application in high-sensitivity and ultrafast ultraviolet photodetectors

http://l03.iphy.ac.cn/l03/papers/2013/WL_AO.pdf

High-sensitivity SrTiO3 photodetectors with paralleled multiple interdigital electrode cells

The side-illumination-enhanced photovoltaic effect has been studied in La0.9Sr0.1MnO3/Si heterojunctions fabricated by laser molecular beam epitaxy. When a He–Ne laser illuminated the La0.9Sr0.1MnO3 film surface, a stable photovoltage was produced and the responsivity is ~0.17 mV mW−1. An enhancement of the photovoltaic effect occurred when the La0.9Sr0.1 MnO3/Si interface was illuminated directly by side illumination, and the steady responsivity reached ~6.87 mV mW−1. This work demonstrates an effective way to improve the photovoltaic responsivity of the perovskite oxide heterojunctions.

/pdf/enhancement-of-photovoltaic-effect-in-la0-9sr0-1mno3-si-2dvwv8q7t2.pdf

Jie Xing

Papers

Highly sensitive fast-response UV photodetectors based on epitaxial TiO2 films

Solar-blind deep-ultraviolet photodetectors based on an LaAlO 3 single crystal

Ultraviolet fast-response photoelectric effects in LiTaO 3 single crystal

High-sensitivity SrTiO3 photodetectors with paralleled multiple interdigital electrode cells

Enhancement of photovoltaic effect in La0.9Sr0.1MnO3/Si heterojunction by side illumination