In the past few years a lot of work has been done on the spectral photoconductivity versus temperature and composition in the semimagnetic semiconductor CdMnxTe /1 to 8 / . In the case of high Mn concentration ( x > 0.5) Lascaray et al. / 6 / have explained the spectral photoconductivity b y taking into account the intra Mn transition 6A1 + (4T1, 4T2). When these transitions appear, because of the competition with the intrinsic absorption, the number of electrons excited in the conduction band decreases and the photocurrent decreases as well. This explains the appearance of a peak in the PC spectra for energies lower than the intra Mn transition. For lower x, the gap decreases and the energy of (6A1, 4T1) is higher than the gap energy. These authors have observed a drastic effect of the frequency and applied electric field on the shape of PC spectra. They have interpreted these results in the framework of a two-level system involving a recombination level Es and a sensitizing trap center E,, as introduced b y Bube / 9 / to explain the important PC of 11-VI compounds.In this work by using transient photoconductivity we show that there exist two rather different lifetimes ( b y an order of magnitude), which could support the existence of two different levels in the gap with different roles. 1-xThe growth technique and the structural characterisations of these samples have been already described / l o / . The ohmic contacts were obtained by a gold chemical deposition at 250 O C in hydrogen vapor during 3 min.A pulse of monochromatic light is sent at room temperature on the sample. The pulse is given by a dye laser. The width of the pulse is 10 ns. The wavelength can be adjusted between 360 and 740 nm.When the laser beam is stopped, the photoconductivity decreases and we study this decreasing with time. Several compositions were studied, namely x = 0 . 7 2 , x = 0.52, x = 0 . 3 0 , and x = 0.115.A iypical experimental curve is given on Fig. 1. One can see the same behaviour for other compositions.In order to get quantitative results, the P S ( t ) curves were analysed following the expression I = Z A. exp(-t/T.). The time constant T . was determined for each ) Place Euggne
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.