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Ga2O3, as an ultra-wide band gap material with physical properties such as large atomic number, low intrinsic carrier density, and high irradiation tolerance, has shown great potential in X-ray detection. This letter reports a self-powered X-ray detector based on vertical p-NiO/Ga2O3 heterojunction diodes (HJDs). Benefiting from the high quality and high built-in potential of the p-n heterojunction, the HJD detector exhibited a pronounced photovoltaic response to X-rays at 0 V with a sensitivity of 212 nC $\cdot $ Gy $^{-1}\cdot $ cm−2 and a fast response time of less than 0.02 s in transient X-ray response measurements, which was much faster than that of the reported Ga2O3 Schottky barrier diode (SBD) detector. The power-voltage (P-V) test indicated that the device conformed to typical photovoltaic characteristics with a maximum output power of 2.95 nW. Moreover, the HJD detector showed a good linear property to various X-ray dose rates from 0.0383 Gy $\cdot \text{s}^{-1}$ to 1.149 Gy $\cdot \text{s}^{-1}$ .

Compared with the widely reported MAPbBr3single crystals, formamidinium-based (FA-based) hybrid perovskites FAPbBr3(FPB) with superior chemical and structure stability are expected to be more efficient and perform as more reliable radiation detectors at room temperature. Here, we employ an improved inverse temperature crystallization method to grow FPB bulk single crystals, where issues associated with the retrograde solubility behavior are resolved. A crystal growth phase diagram has been proposed, and accordingly, growth parameters are optimized to avoid the formation of NH4Pb2Br5secondary phase. The resulting FPB crystals exhibit a high resistivity of 2.8 × 109Ω·cm and high electron and hole mobility–lifetime products (μτ) of 8.0 × 10–4and 1.1 × 10–3cm2·V–1, respectively. Simultaneously, the electron and hole mobilities (μ) are evaluated to be 22.2 and 66.1 cm2·V–1·s–1, respectively, based on the time-of-flight technique. Furthermore, a Au/FPB SC/Au detector is constructed that demonstrates a resolvable gamma peak from 59.5 keV 241Am γ-rays at room temperature for the first time. An energy resolution of 40.1% is obtained at 30 V by collecting the hole signals. These results demonstrate the great potential of FAPbBr3as a hybrid material for γ-ray spectroscopy and imaging.

Halide perovskites have been considered as nuclear radiation detection materials due to their high mobility, long carrier lifetime, and high absorption coefficient. However, it has been reported that the ion migration increases the dark current of halide perovskite detectors and hinders the stable response to high energy photons or particles. In this work, we report the utilization of the “voltage cycling” technique to obtain the stable α-particle spectra in a CsPbBr2.4Cl0.6device. Also, by measuring the time-dependent stability and the effect of electric field strength, we can gain insight into the phenomona causing instability in these devices. Accordingly, the influence of ion migration on the charge transport properties and energy spectra in CsPbBr2.4Cl0.6detectors was also revealed. Our investigation demonstrates the strong correlation between ion migration processes and stable energy spectra in halide perovskite materials.

The all-inorganic halide perovskite CsPbBr3has attracted significant attention for applications of high-performance and stable solar cells, light-emitting diodes (LEDs), and photoelectric and X-/γ-ray detectors. The discrepant photoelectric properties are confusing, which strongly implies that the perovskite is sensitive to defects. Here, novel and ubiquitous defects, “twin domains”, are reported in solution-grown CsPbBr3single crystals on the basis of X-ray diffraction techniques, optical microscopy, and transmission electron microscopy (TEM). Two kinds of orthorhombic domain structures, {121} reflection twins and 90° rotations along [101̅], are identified in as-grown CsPbBr3crystals. In situTEM results indicate that these domains are ferroelastic, which are related to the spontaneous strain induced by a phase transition. During a phase transition from parent cubic (m3̅m) to tetragonal (4/mmm), the loss of cubic {110} reflection planes, the 4-fold rotation axis (4), or the 3-fold rotoinversion axis (3̅) could act as a twin law and account for the appearance of domain walls. Further reduction of symmetry to orthorhombic (mmm) and the losses of the tetragonal 4-fold rotation axis (4) and mirror plane {101} lead to the emergence of [101̅] rotations and {101} reflection twins, respectively. Our work not only enhances the understanding of defects in CsPbBr3, which opens the door for the further optimization of photoelectric applications, but also provides a way to tailor it.

The all-inorganic halide perovskite CsPbBr3exhibited extraordinary photoelectric properties as well as great potential for various optic-electronic devices. The introduction of a Cl/I dopant is an effective method to optimize their properties. However, it is still a challenge to grow doped CsPbBr3single crystals from solution. In this work, we report on the crystal growth of Cl/I-doped CsPbBr3crystals using the modified inverse temperature crystallization (ITC) method. The components of raw materials and solvent in precursors were precisely tailored. The resulting doping ratio between the actual content and the nominal content are 0.99 and 0.046 for Cl and I, respectively. It indicates that I ion doped crystals exhibit more severe stoichiometric deviation due to the lower decomposition energy. The crystal structure, morphology, and optical properties of doped crystals were also investigated systematically. The {101} and {010} facets of as-grown crystals were influenced by the doping process. PL and UV transmittance spectra exhibited changes in the band gap in Cl/I-doped crystals. Finally, the phase diagram of basic photoelectric properties was determined for CsPb(Br1–nCln)3crystals and it reveals conductive type changes from the P type to N type with an increase in the doping content of the Cl element. The optimum component of CsPb(Br0.93Cl0.07)3demonstrates the highest resistivity of 4.3 × 109Ω cm, an on/off ratio of ∼40, and a mobility of 414 cm2V–1s–1as well as the lowest carrier concentration of 3.57 × 107cm–3. Our work provides a strategy to grow doped halide perovskite crystals and tailor their optical and electrical properties.

A CsPbBr3single crystal exhibits great potentials in X-ray/gamma-ray spectroscopy and imaging. Here, an inverse temperature crystallization (ITC) method with modified precursor composition is proposed to prepare CsPbBr3single crystals. The introduction of adduct PbBr2·2DMSO, synthesized by the antisolvent vapor-assisted crystallization method, in the precursor solution gives rise to superior crystallization with a lower impurity concentration and higher resistivity of 6.37 × 109Ω·cm, as well as a higher hole mobility (50.7 cm2·V–1·s–1). Furthermore, a low dark current of 2.3 nA is obtained at a bias of −100 V based on an as-grown crystal with a thickness of 1 mm, according to the asymmetric Au/CsPbBr3/Sn structure. The resulting asymmetric planar detectors achieve the high peak-to-valley ratio pulse height spectra with an energy resolution of 7.66%, illuminated by an uncollimated 241Am@5.5 MeV α particle. Simultaneously, an energy resolution of 13.5% is realized when irradiated by a 59.5 keV 241Am γ-ray source at room temperature. The thermally stimulated current (TSC) spectra indicate that the density of deep energy-level trap is significantly reduced in the CsPbBr3crystals grown by PbBr2·2DMSO-modified precursor solution, which is consistent with the high performance in radiation detection.