Photosensitized Deep Gap Center Relaxation in Amorphous Selenium Layers Containing As Additions

Abstract

The effect of preexcitation with light of band gap energy on deep trapping and thermal generation is examined in selenium and selenium-rich As-Se alloy films by time-of-flight and xerographic techniques. Results suggest that excess carrier trapping and dark carrier generation are controlled by deep defect centers whose population can temporarily be altered by photoexcitation. ~CCJIeAOBaHO BJlIIRHHe IlpeABapHTeJlbHOrO ,,30HHOrO'' OCBe~eHUII H a m y 6 o~~i i 3aXBaT II TePMIIYeCKYH) reHepaqHH) B CJIOIIX CeJIeHa B CJIOIIX COeAIIHeHB~ As-Se IlOCpeACTBOM A3MepeHEIII BpeMRIIpOneTHbIX II KCepOrpa@II9eCKIIX IIapaMeTpOB. Pe3yJIbTaTbI CBHAeTeJIbCTByIoT 0 TOM, YTO 3aXBaT HepaBHOBeCHbIX HOCHTeneii 3apma II TeMHOBaR TepMHYeCKaII RHepaWII KOHTpOJlHpyeTCR ~J I~~O K H M H Ae@eKTHbIMB QeHTpaMH, 3aCeJleHHOCTb KOTOPbIX H3MeHReTCR npH @OTOB036YXAeHHII.' ) The photodarkening in amorphous selenium at low temperatures was firstly analyzed by Averyanov et al. [9] and Tanaka and Odajima [lo].

Time-of-Flight Experiments in Amorphous Chalcogenide Semiconductors

“…4.19(b)), the transit for the As 0.4 Se 0.6 layer could be accurately assessed. These results are in good agreement with our previous data on monolayers [42] and the data of other investigators [20,24,43]. The time designated with an arrow is used as a transit time.…”

Xerographic spectroscopy of gap states in Se-rich amorphous semiconductors review

“…Furthermore, the parameters mentioned (residual potentials V Rl and V RS ) increase with exposure time. The effects of pre-illumination with band-gap light on the main xerographic characteristics for the case of pure amorphous selenium were examined in details by Abkowitz and Enck in their extensive work [35] and, for Se-rich a-As x Se 1 − x and a-Sb x Se 1 − x alloys, by the present authors [51,52,[58][59][60][61][62][63][64][65][66][67][68]. Clearly, exposure to white light generates an appreciable concentration of deep hole traps.…”

“…Measurements performed by the present authors readily discern photo- and thermostructural effects on gap state population (see, e.g. [51,52,[58][59][60][61][62][63][64][65][66][67][68] and Refs. therein).…”

“…On the basis of the data in Fig. 20, by analogy to the photocurrent transients [58,59,61], the relaxation functions ϕ(τ)=…”

“…(1) Dark-rested sample, (2) after white light exposure 5000 lx × 60 s. Table 3 Surface potential dark decay parameters in a-As x Se 1 − x films. It is of particular significance that "memory" effects are influenced not only by variation of composition, but also by electric fields [59,61,[66][67][68]. For example, Fig.…”