Showing papers by "Baojie Yan published in 1995"
TL;DR: In this paper, the authors investigated the post-transit time-of-flight photocurrents in space-charge-limited current mode and found that the frequency pre-factor ν 0 varies between 1011 Hz and 1013 Hz, with corresponding activation energies in the range of 0.42 to 0.52 eV.
Abstract: Electron emission from deep states in the intrinsic layer of a‐Si:H p‐i‐n structures was investigated by post‐transit time‐of‐flight photocurrents in space‐charge‐limited current mode. The emission time tE from the deep levels is thermally activated for temperatures above 250 K. The frequency pre‐factor ν0 (attempt‐to‐escape frequency) varies between 1011 Hz and 1013 Hz, with the corresponding activation energies Ea in the range of 0.42 to 0.52 eV for our samples. A Meyer–Neldel relation between ν0 and Ea is observed. Below 250 K, tE becomes less temperature sensitive. The density of states in the upper part of the gap is evaluated from the current in the post‐extraction regime. At low temperature, the resolved distribution of gap states becomes inconsistent with higher‐temperature data, similar to what is observed by standard post‐transit photocurrent analysis. Possible mechanisms for the observed behavior of both the tE and the density of states are discussed: re‐trapping, hopping‐assisted release from ...
18 citations
TL;DR: In this article, the transient forward current in several specimens of a-Si:H p-i-n structures was studied as a function of applied voltage, temperature, and illumination as well as the degradation of the samples.
Abstract: The transient forward current in several specimens of a-Si:H p-i-n structures was studied as a function of applied voltage, temperature, and illumination as well as the degradation of the samples. The results show that the delay time of the current onset from its initial decay relates to the initial electron space-charge-limited current with a power law, td α (ISCLC)−γ, where γ is a constant which is insensitive to the measurement conditions such as temperature and illumination but depends on the properties of devices such as the density of states in the intrinsic layer. Therefore, the value of γ is a measure of the quality of devices. The current-response time product, Iftr, is largely independent of the applied voltage for specific samples.
3 citations
TL;DR: In this paper, a full and detailed transient space-charge-limited current (T-SCLC) study of a-Si:H p-i-n diodes has been carried out in the time range from 108s to 10s.
Abstract: A full and detailed transient space-charge-limited current (T-SCLC) study of a-Si:H p-i-n diodes has been carried out in the time range from 108s to 10s. In the short-time regime, general features of T-SCLC such as the current cusp and the carrier extraction period were observed, and related transport parameters were deduced. Electron emission from deep states was studied by measuring the current transients well beyond the extraction time. The emission time is thermally activated at temperatures higher than 250K and levels off at lower temperatures. The high temperature behaviour places the upper edge of the deep states at 0.42–0.52eV below the conduction band edge, and the attempt-to-escape frequency in the range of 1011-1013Hz. An observed shift of emission time with light intensity is attributed to defect relaxation.
2 citations