Space charge limited electron transport in AlGaN photoconductors

Abstract

Electrical properties and deep traps spectra of N-polar and Ga-polar AlGaN films grown by molecular beam epitaxy in a wide composition range Electrical properties and photoresponse of AlGaN based photodetectors were studied demonstrating an adverse effect of the broad-band trap distribution on the spectral, electrical, and time-response characteristics. It was found that n-type conduction mechanism is space charge limited indicating a strong carrier trapping effect. In particular, we show that dark current, photoresponsivity, and response time are determined by the slow-varying energy distribution of traps located above the equilibrium Fermi level. We demonstrate also that both the deep recombination centers and the localized shallow states do not impact the response time of the photodetector, and the persistent photocurrent effect is directly connected to the voltage-induced injection and trapping of the excess carriers.

Demonstration of an AlGaN-based solar-blind high-voltage photoconductive switch

“…10 Recently, Cicek et al enhanced the QE of AlGaNbased p-i-n photodetectors up to a remarkable high value of 89%. 11 Nevertheless, up to now all reported AlGaN-based photodetectors are working in low bias mode (lower than 100 V), 12 while high voltage operation (up to 500 V) of AlGaN-based solar-blind devices has never been reported. In this work, a solar-blind PCSS with promising performance is first demonstrated based on semi-insulating AlGaN film.…”

Nitride‐based hetero‐field‐effect‐transistor‐type photosensors with extremely high photosensitivity

“…High‐performance emitters, such as UV‐ 4, blue‐, green‐, and white‐light‐emitting diodes and violet‐, blue‐, and green‐laser diodes 5, have already been achieved using these materials. In contrast, although there have been several reports of nitride‐based photodetectors, such as photoconductors 6, Schottky photovoltaic detectors 7, pin photodiodes 8, solar cells 9, 10, and photo field‐effect transistors 11, no appropriate devices with both a high photosensitivity and a high S/N ratio have been realized. In addition, with the exception of solar cells, most devices only exhibit photosensitivity in the UV region, and cannot detect light in the visible region.…”

Electric field dependence of thermal activation energy in poly(4TBU)/poly(methyl)methacrylate blend

“…Researchers are concentrating on the fundamental aspects of carrier transport in these materials for a better understanding of the behavior as no single theory could satisfactorily explain the observations in different materials. The regime of space charge limited conduction is of much importance due to the ease with which one can deduce material parameters like carrier mobility, trap distribution etc [1], [2], [3]. In this work we studied the nature of thermal activation energy in a new fluorescent semiconducting polymer poly(6-tbutyl-3,4-dihydro-2H-1,3-benzoxazine) (poly(4TBU) in the ohmic as well as the space charge limited current (SCLC) region and found that the activation energy undergoes an interesting transition with the field.…”