The operating mode of a planar Cd(Zn)Te device in its most basic form consists of two electrodes, one of which is biased under negative potential while the other which is typically connected to a charge sensitive pre-amplifier for signal amplification. It is also usually required that the detectors have sufficiently high resistivity such that the leakage current induced by the operating voltage is sufficiently low. However, it is not enough to have material with high bulk resistivity. Surface preparation has a strong effect on the electronic properties of the device and is of paramount importance to achieve functioning and reproducible detectors. The effect of anode and cathode surface morphology on detector performance has been investigated by A. Hossain et al. (1). Furthermore the effects of using different chemical etchants for electrode surface preparation has been investigated by (2) Cd(Zn)Te. Finally, the effect of lateral edge morphology on device leakage current has been demonstrated by Crocco et al. (3). Despite these recent advancements in preparing the surface of Cd(Zn)Te devices for detector applications, large asymmetries in the electronic properties of Cd(Zn)Te detectors are quite common. Indeed, we have observed differences in leakage current several orders in magnitude depending on which electrode of the planar configuration is used as the cathode. In fact, this phenomenon has been observed for both oriented as well as non-oriented crystals. Therefore an understanding of the material properties which contribute to this asymmetry is of paramount importance from a detector fabrication perspective. For the development of patterned electrode geometries, correct selection of this surface is crucial. In the case of oriented crystals, it has been observed that the (111)A and (111)B surface terminations may have some influence on the electrical properties of the device. Shown below in Fig. 1 is the structure of (111) oriented Cd(Zn)Te, showing the alternating crystallographic planes of Cd(Zn) and Te atoms. Taking into account the unit cell of the crystal, the surface which will terminate in Te is referred to as the (111)B surface, and the surface which will terminate in Cd(Zn) is the (111)A surface.
J. Crocco, H. Bensalah, Q. Zheng, V. Corregidor, E. Avles, A. Castaldini, et al. (2012). STUDY OF ASYMMETRIES OF CZT DEVICES INVESTIGATED USING PICTS, RBS, SPS, AND GAMMA RAY SPECTROSCOPIES. JOURNAL OF APPLIED PHYSICS, 112, 074503-074512 [10.1063/1.4754448].
STUDY OF ASYMMETRIES OF CZT DEVICES INVESTIGATED USING PICTS, RBS, SPS, AND GAMMA RAY SPECTROSCOPIES
FRABONI, BEATRICE;CAVALCOLI, DANIELA;CAVALLINI, ANNA;
2012
Abstract
The operating mode of a planar Cd(Zn)Te device in its most basic form consists of two electrodes, one of which is biased under negative potential while the other which is typically connected to a charge sensitive pre-amplifier for signal amplification. It is also usually required that the detectors have sufficiently high resistivity such that the leakage current induced by the operating voltage is sufficiently low. However, it is not enough to have material with high bulk resistivity. Surface preparation has a strong effect on the electronic properties of the device and is of paramount importance to achieve functioning and reproducible detectors. The effect of anode and cathode surface morphology on detector performance has been investigated by A. Hossain et al. (1). Furthermore the effects of using different chemical etchants for electrode surface preparation has been investigated by (2) Cd(Zn)Te. Finally, the effect of lateral edge morphology on device leakage current has been demonstrated by Crocco et al. (3). Despite these recent advancements in preparing the surface of Cd(Zn)Te devices for detector applications, large asymmetries in the electronic properties of Cd(Zn)Te detectors are quite common. Indeed, we have observed differences in leakage current several orders in magnitude depending on which electrode of the planar configuration is used as the cathode. In fact, this phenomenon has been observed for both oriented as well as non-oriented crystals. Therefore an understanding of the material properties which contribute to this asymmetry is of paramount importance from a detector fabrication perspective. For the development of patterned electrode geometries, correct selection of this surface is crucial. In the case of oriented crystals, it has been observed that the (111)A and (111)B surface terminations may have some influence on the electrical properties of the device. Shown below in Fig. 1 is the structure of (111) oriented Cd(Zn)Te, showing the alternating crystallographic planes of Cd(Zn) and Te atoms. Taking into account the unit cell of the crystal, the surface which will terminate in Te is referred to as the (111)B surface, and the surface which will terminate in Cd(Zn) is the (111)A surface.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
