Compensation mechanisms in CdTe crystals doped with Cr
|Eugene Nikonyuk 2, Zinaida Zakharuk 1, Anna Rarenko 1, Evgene Rybak 1, Mykola Kuchma 2, Margaryta Kovalets 2|
1. Chernivtsi National University (ChNU), 2 Kotsubinsky Str., Chernivtsi 58012, Ukraine
It is known that Cr ions enter into CdTe crystals in different charge states. Moreover, chromium impurity in CdTe shows a tendency to form in clusters. Thus, properties of cadmium telluride doped with Cr strongly depend on impurity behavior in material and are of much scientific interest. In the work we present the investigation of electrophysical and optical properties of CdTe:Cr samples. Most of the CdTe:Cr samples under study posses p-conductivity type with carrier concentration of p=1011-1014 cm-3, that is in several orders less then in undoped CdTe. Ionization energies of the acceptors governing the crystals conductivity increase from 0,19 eV to 0,32 eV with hole concentration increasing. High level compensation (k=0,99) of acceptors is observed in this case. An energy model with a number of deep levels in the band gap well explaining electrical and optical properties of CdTe doped with Cr is proposed. Experimental studies allow us to conclude that chromium in p-type CdTe crystals is in a single charged Cr+ state. n-type conductivity in several CdTe crystals can be explained by the presence of overlapping space charge regions due to the clusters of chromium atoms.
Presentation: poster at E-MRS Fall Meeting 2004, Symposium F, by Zinaida Zakharuk
See On-line Journal of E-MRS Fall Meeting 2004
Submitted: 2004-04-29 15:37 Revised: 2009-06-08 12:55