Depletion region

About: Depletion region is a research topic. Over the lifetime, 9393 publications have been published within this topic receiving 145633 citations.

XBn Barrier Photodetectors for High Sensitivity and High Operating Temperature Infrared Sensors

Abstract: A barrier photodetector is a device in which the light is absorbed in a narrow bandgap semiconductor layer whose bands remain essentially flat or accumulated at the operating bias so that all carrier depletion is excluded. In a conventional photodiode below a threshold temperature T0, typically 130-150K for MWIR devices, the dark current is due to Generation-Recombination (G-R) centres in the depletion layer. In a barrier detector, the absence of depletion in the narrow bandgap semiconductor ensures that the G-R contribution to the dark current is negligible. The dark current in the barrier detector is thus dominated by the diffusion component, both above and below T0. Therefore, at a given temperature below T0, a barrier detector will exhibit a lower dark current than a conventional photodiode with the same cut-off wavelength. Alternatively, for a given dark current, a barrier detector will operate at a higher temperature than a conventional photodiode, provided that this temperature is below T0. Device architectures are presented for barrier detectors with photon absorbing layers based on InAs1-xSbx alloys and type-II InAs/GaSb superlattices (T2SL). The thermionic and tunneling components of the dark current are analyzed and shown to be negligible for typical device parameters. An operating temperature of ~150K is estimated for a MWIR barrier detector with f/3 optics and a cut-off wavelength of 4.2μ.

Investigation of the double exponential in the current—Voltage characteristics of silicon solar cells

Abstract: The influence of minority carrier recombination in the depletion region of silicon solar cells on their current-voltage characteristics has been investigated. Starting with cells which exhibited a clear double-exponential dark characteristic of the form j = j_{01}[\exp (\frac{qV}{(A_{1}kT})-1] + j_{02}[\exp (\frac{qV}{A_{2}kT})-1] + \frac{V}{R_{sh}} with values A_{1} \approx 1 , A_{2} \approx 2 , and R sh large, depletion region recombination was studied by subjecting the cells to proton irradiation of 20- to 80-MeV energy at fluences of 1012to 1015cm-2, so as to introduce further recombination centers in the depletion region. A significant change of j 01 resulted rather than the expected change in j 02 which would be caused by the introduction of deeplying levels. It could be shown that this effect, included inthe Sah, Noyce, Shockley formulation of diode current resulting from recombination in the depletion region, Was caused by the introduction of shallow levels in the depletion region by the proton irradiation. The analysis required an accurate measurement of the I-V Characteristics over a range of temperatures and an evaluation of them with a least squares Curve fitting computer program in order to separate the effects. As a result of this study it is found that the saturation current j 01 is not necessarily attributable Only to diffusion current from outside the depletion region and that solely its temperature dependence can clarify its origin.

Grain Boundary Defect Chemistry of Acceptor‐Doped Titanates: Space Charge Layer Width

Abstract: The grain boundary space charge depletion layers in acceptor-doped SrTiO3 and BaTiO3 ceramics were investigated by impedance spectroscopy in the time and frequency domain. Based on the layer width and its dependence on the acceptor concentration, the temperature, and the oxygen partial pressure during annealing, a suggestion for a refined Schottky model is proposed. The local distribution of the donor-type grain boundary states causing the depletion layer and the resulting band bending are discussed.

High-temperature cubic boron nitride p-N junction diode made at high pressure.

Abstract: A p-n junction diode of cubic boron nitride was made by growing an n-type crystal epitaxially on a p-type seed crystal at a pressure of 55 kilobars and a temperature of about 1700°C. A temperature-difference solvent method was used for the crystal growth, and beryllium and silicon were doped as acceptors and donors, respectively. Formation of the p-n junction was clearly confirmed at 1 bar by rectification characteristics and by existence of a space charge layer of the junction as observed by electron beam induced current measurement. This diode operated at 530°C.