Search results for "Deep level"
showing 6 items of 6 documents
Transport measurements in InSe under high pressure and high temperature: shallow-to-deep donor transformation of Sn related donor impurities
2003
We have investigated the temperature dependence of the transport parameters of Sn-doped InSe at different pressures, up to 2.5 GPa. A noticeable change in the temperature dependence of all the transport parameters has been observed above 1.2 GPa. This fact is explained by assuming the transformation of Sn shallow donors into deep donors at a hydrostatic pressure of 1.1 GPa, and by taking into account the transfer of electrons from the absolute minimum to higher energy minima in the conduction band. At ambient pressure, the position of the Sn deep level is estimated to lie 75 ± 20 meV above the absolute conduction-band minimum.
Tin-related double acceptors in gallium selenide single crystals
1998
Gallium selenide single crystals doped with different amounts of tin are studied through resistivity and Hall effect measurements in the temperature range from 30 to 700 K. At low doping concentration tin is shown to behave as a double acceptor impurity in gallium selenide with ionization energies of 155 and 310 meV. At higher doping concentration tin also introduces deep donor levels, but the material remains p-type in the whole studied range of tin doping concentrations. The deep character of donors in gallium selenide is discussed by comparison of its conduction band structure to that of indium selenide under pressure. The double acceptor center is proposed to be a tin atom in interlayer…
Defect spectroscopy of single ZnO microwires
2014
The point defects of single ZnO microwires grown by carbothermal reduction were studied by microphotoluminescence, photoresistance excitation spectra, and resistance as a function of the temperature. We found the deep level defect density profile along the microwire showing that the concentration of defects decreases from the base to the tip of the microwires and this effect correlates with a band gap narrowing. The results show a characteristic deep defect levels inside the gap at 0.88 eV from the top of the VB. The resistance as a function of the temperature shows defect levels next to the bottom of the CB at 110 meV and a mean defect concentration of 4 1018 cm3 . This combination of tech…
Annealing-induced Changes in the Electronic and Structural Properties of ZnTe Substrates
2000
The aim of this study is to demonstrate that the electronic and structural properties of II–VI substrates, here ZnTe, can be dramatically affected by thermal heating at temperatures in the range of those typically used in the epitaxial metalorganic chemical vapor deposition processes. Photoluminescence response shows that annealing at these temperatures produces a reduction of the sample crystalline quality, decreasing the free exciton emission relative to the deep level related one. Some factors, like the change in the charge and stress state of dislocations, Cu diffusion, and oxygen incorporation, could be responsible for changes in the substrate properties, which can produce stresses and…
Defect incorporation in In-containing layers and quantum wells: Experimental analysis via deep level profiling and optical spectroscopy
2020
Abstract Recent studies demonstrated that the performance of InGaN/GaN quantum well (QW) light emitting diodes (LEDs) can be significantly improved through the insertion of an InGaN underlayer (UL). The current working hypothesis is that the presence of the UL reduces the density of non-radiative recombination centers (NRCs) in the QW itself: during the growth of the UL, surface defects are effectively buried in the UL, without propagating towards the QW region. Despite the importance of this hypothesis, the concentration profile of defects in the quantum wells of LEDs with and without the UL was never investigated in detail. This paper uses combined capacitance-voltage and steady-state pho…