The synthesis, crystal growth, and structural and optoelectronic characterization has been carried out for the perovskite compound CsPbBr3. This compound is a direct band gap semiconductor which meets most of the requirements for successful detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response, with detector resolution comparable to that of commercial, state-of-the-art materials. A structural phase transition which occurs during crystal growth at higher temperature does not seem to affect its crystal quality. Its μτ product for both hole and electron carriers is approximately equal. The μτ product for electrons is comparable to cadmium zinc telluride (CZT) and that for holes is 10 times higher than CZT.

Crystal Growth of the Perovskite Semiconductor CsPbBr3: A New Material for High-Energy Radiation Detection

The potential of SiC and diamond for producing microwave and millimeter-wave electronic devices is reviewed. It is shown that both of these materials possess characteristics that may permit RF electronic devices with performance similar to or greater than what is available from devices fabricated from the commonly used semiconductors, Si, GaAs, and InP. Theoretical calculations of the RF performance potential of several candidate high-frequency device structures are presented: the metal semiconductor field-effect transistor (MESFET), the impact avalanche transit-time (IMPATT) diode, and the bipolar junction transistor (BJT). Diamond MESFETs are capable of producing over 200 W of X-band power as compared to about 8 W for GaAs MESFETs. Devices fabricated from SiC should perform between these limits. Diamond and SiC IMPATT diodes also are capable of producing improved RF power compared to Si, GaAs, and InP devices at microwave frequencies. RF performance degrades with frequency and only marginal improvements are indicated at millimeter-wave frequencies. Bipolar transistors fabricated from wide bandgap material probably offer improved RF performance only at UHF and low microwave frequencies. >

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The potential of diamond and SiC electronic devices for microwave and millimeter-wave power applications

A summary is presented of the present status of several compound semiconductor radiation detectors, including detectors fabricated from GaAs, HgI2, CdTe, Cd1−xZnxTe and PbI2

Room-temperature compound semiconductor radiation detectors

Properties of gallium selenide single crystal

Electronic applications of semiconductor diamonds are addressed. Doping and electrical properties of these films, formation of low-resistive 'ohmic' contacts, surface modification methods, and experimental device applications are discussed. Of particular interest are high-temperature (300 degrees C) MOSFETs and metal contacts to CVD (chemical vapor deposition) diamond films which were used to fabricate high-temperature (580 degrees C) Schottky diodes, rudimentary MESFETs, and blue light-emitting diodes (LEDs). The status of the emerging technology is reviewed with an emphasis on the areas of current research activity. >

The electrical properties and device applications of homoepitaxial and polycrystalline diamond films

Electrical properties and performances of natural diamond nuclear radiation detectors

Electron and hole trapping centres of GaSe(I2) grown by chemical transport method are investigated by using photoelectronic techniques, such as thermally stimulated current (TSC), thermal quenching of photoconductivity (TQ) and spectral response of photoconductivity. Several electron trapping centres, between 0.15 and 0.65 eV below the conduction band, with densities ranging from 1013 to 1016 cm−3 and capture cross-sections between 10−13 and 10−19 cm−2 are found. Three hole trapping centres, acting as sensitizing centers for photoconductivity, are also present at 0.40, 0.27, and 0.21 eV above the valence band. They are responsible for a superlinearity in the behaviour of the photocurrent versus light-intensity at low temperature.



Elektronen- und Locherhaftstellen von GaSe(J2), das durch chemische Transportmethoden gezuchtet wurde, werden mit photoelektrischen Methoden, wie thermisch stimulierte Strome (TSC), thermische Tilgung der Photoleitung (TQ) und spektrale Abhangigkeit der Photoleitung, untersucht. Verschiedene Elektronenhaftzentren zwischen 0,15 und 0,65 eV unterhalb des Leitungsbandes, Dichten von 1013 bis 1016 cm−3 und Wirkungsquerschnitten zwischen 10−13 und 10−19 cm−2 werden gefunden. Drei Locherhaftstellen, die als Sensibilisierungszentren fur die Photoleitung wirken, sind ebenfalls vorhanden bei 0,40, 0,27 und 0,21 eV oberhalb des Valenzbandes. Sie sind verantwortlich fur eine Superlinearitat im Verhalten der Photostrom-Lichtintensitatscharakteristik bei tiefen Temperaturen.

Photoelectronic properties of n-GaSe

PbI2 detectors fabricated starting from samples either grown from the melt by the Bridgman method either from the vapour by the iodine assisted chemical transport method, have been tested for nuclear applications and compared each other in this respect. Values of (mobility) × (trapping times) product, ??+, measured both for electrons and holes turn out to be one or two orders of magnitude larger than reported previously and they are better for vapour-grown samples than for melt-grown ones. Moreover, dark currents seem to be one or two orders of magnitude lower for samples grown from the vapour-phase. The indication is obviously that, at least at this early stages, the growth by the chemical transport seems to be superior to the Bridgman method for obtaining detector quality crystals. Finally, the main features of this material as nuclear detector are discussed.

A. Quirini

Papers

Electrical properties and performances of natural diamond nuclear radiation detectors

Photoelectronic properties of n-GaSe

PbI2 as Nuclear Particle Detector

A particular application of GaSe semiconductor detectors in the neutrino experiment at CERN

Space-charge limited currents in n-GaSe crystals