Transient properties of PINIP structures in three-terminal a-Si : H based three-color detectors

a-Si:H-based three-terminal three-color detectors are experimentally invest igated. Transient properties of photocurrent after bias switching are studi ed in PINIP structures for the detection of either blue and green light (PI 1NI2P) or green and red light (PI2NI3P) under different illumination intens ities and under different voltages before and after bias switching. A recip rocal relationship between the delay times and the illumination intensity i s established for both structures over a wide range of illumination intensi ty. Only for the larger intensities is a deviation from the reciprocal rela tion observed. The delay time, t(d Np), due to switching from negative to p ositive bias, determines the speed of the device. It is for both structures only moderately wavelength dependent, but it strongly depends on the switc hing voltage levels, V-N(egitive) and V-p(ositive). Optimized selection of V-1N and V-1p reduces the delay time of the PI1NI2P structure, speeding it up to the generally faster PI2NI3P structure. (C) 2000 Elsevier Science B.V . All rights reserved.