Contacts for High-Resistivity (Cd,Mn)Te Crystals

Abstract

Abstract-Semi-insulating (Cd,Mn)Te crystals offer a material that may compete well with the commonly used (Cd,Zn)Te crystals for manufacturing large-area X-and gamma-ray detectors [1]. The Bridgman growth method yields good quality, high-resistivity (10 9 -10 10 Ω·cm) crystals of (Cd,Mn)Te:V. Doping the as-grown crystals with the compensating agent vanadium (≈ 10 16 cm -3 ) ensures their high resistivity; thereafter, annealing them in cadmium vapors reduces the number of cadmium vacancies. Applying the crystals as detectors necessitates having satisfactory electrical contacts. Accordingly, we explored various techniques of ensuring good electrical contacts to these semi-insulating (Cd,Mn)Te crystals, assessing metallic layers, monocrystalline semiconductor layers, and amorphous (or nanocrystalline) semiconductor layers. We found that ZnTe heavily doped (≈ 10 18 cm -3 ) with Sb, and CdTe heavily doped ( ≈ 10 17 cm -3 ) with In, proved satisfactory semiconductor contact layers. They subsequently enabled us to establish good contacts (with only narrow tunneling barriers) to the Au layer that usually constitutes the most external contact layer. We outline our technology of applying electrical contacts to semiinsulating (Cd,Mn)Te, and describe some important properties.

Charge transport properties of CdMnTe radiation detectors

“…A very recent and promising candidate is cadmium manganese telluride (CMT) [3]. Its distinct advantages of good compositional homogeneity and a highly tunable band gap compared to CdZnTe have encouraged CMT detector developments in recent years, bringing large improvements in the performance of CMT as a high resistivity single crystal radiation detector [4][5][6][7][8][9][10]. This work describes the growth, fabrication and characterization of indium doped CMT radiation detectors with 5 % manganese concentration (1.59 eV band gap).…”