Investigation of deep levels in high-resistivity bulk materials by photo-induced current transient spectroscopy. I. Review and analysis of some basic problems

Abstract

The use of photo-induced current transients as a means for the detection of deep trapping levels in high-resistivity bulk materials and for the determination of their parameters is discussed. In this perspective some experimental and theoretical problems are discussed on the basis of various models. The conditions which must be satisfied by the kinetics or experimentally in order to observe a quasi-exponential time dependence for the decay of the current corresponding to a single trap are pointed out. Special attention is devoted to various possibilities, depending on the model and on experimental conditions, for the parameters related to the trap or to other centres to be involved in exponential decays and how this can affect the evolution of the transient as a function of temperature. The conclusions of this analysis are of practical importance for the implementation of various possible multigate processing methods of computer recorded transient data, which are evaluated in Part II.

Behavior of deep level defects on voltage-induced stress of Cu(In,Ga)Se 2 solar cells

“…To analyze each peak, the trap energy levels were calculated from the Arrhenius plot of versus [11][12][13] and the energy levels of H1 and H2 are found at 0.18 and 0.29 above the valence band maximum, respectively. The defect type is not as easily discerned only using PICTS measurement and so these two traps (H1 and H2) are identified as majority hole traps by utilizing the DLTS measurement for the cell junction.…”

Transient Photo-Induced Current Measurements in High Resistivity ZnSe Crystals

“…Fig. 2a and 2b show a typical PICT spectra generated by four-gate signal processing [4,6,9]. Four well-separated peaks are revealed indicating the presence of four trapping levels.…”

“…The data can be sampled at 20 000 points with 16-bit accuracy. The stored data were analyzed using the socalled four-gate technique [4][5][6][7][8][9]. In Fig.…”

Photocurrent Transients in Presence of a Double Impurity in Semi-Insulating Semiconductors

“…The temperature was varied in steps of about two degrees. The PICTS spectra were computed using the double gate method [7]. Figure 1 shows PICTS spectra of a typical Mg x Zn 1Àx Te crystal with x 0:14 in the temperature range 100 K T 200 K. The spectrum consists of a broad peak whose temperature position shifts with the rate window (and consequently the emission coefficient e).…”

“…The theoretical basis of the PICTS technique has been discussed by several authors [7,8]. It was recognized that the current decay curves may consist of more than one exponential due to the simultaneous emission of carries from more than one trap level.…”