Effect of side-surface passivation on the electrical properties of metal-Cd(Zn)Te-metal structures Sklyarchuk V. 1 , Fochuk P. 1 , Zakharuk Z. 1 , Grill R. 2 , Kutny V. 3 , Rybka A. 3 , Nakonechny D. 3 , Zakharchenko A. 3 , Nykoniuk Ye. 4 , A. E. Bolotnikov 5 , and R. B. James 5 1 – Chernivtsi National University, 2 Kotsiubynskoho Str., 58012, Chernivtsi, Ukraine 2 – Institute of Single Crystals NASU, 60, Lenina Str., Kharkiv, Ukraine 3 – National Science Ctr., “Kharkov Institute of Physics and Technology”, 1, Akademichna St., Kharkiv, 61108, Ukraine 4 – National University of Water Management and Nature Resources Use, 11 Str. Soborna, Rivne, 33028, Ukraine 5 – Brookhaven National Laboratory, Upton, Bldg. 197D, Upton, NY, USA ABSTRACT We explored the influence of Cd(Zn)Te detectors on the detector’s dark current for different methods of contact formation and passivation of the side surfaces. Our findings suggest that the dark current of a homogeneous detector with ohmic contacts is limited by the detector’s resistivity and the operating voltage. Detectors with a rectifying barrier have a markedly lower dark current at the same voltage and contact geometry than those without such a barrier, and their sides have a larger space charge than those of untreated ones. The major factor lowering the detector’s dark current is the formation of a rectifying barrier that occurs while creating contacts to the detector; the role of passivation of the lateral surface in this case is minimal. However, passivation plays the main role in the formation of leakage current in homogeneous detectors with ohmic contacts, where the uniformity of the electric field is important inside the detector, or in other studies used for determining the bulk resistivity of the detector material. We formed a surface-barrier structure on a semi-insulating Cr-Cd(Zn)Te-Cr crystal (n-type) with a resistivity of 10 10 Ohm-cm at room temperature. The measured leakage current of this detector was less than 3 nA at 1500 V. We discuss our findings on this detector’s structural properties. Keywords: Cd(Zn)Te, semiconductor gamma-radiation detector, I-V curves, contacts, passivation. 1. INTRODUCTION In the last decade, major advances were made in the technology of growing the wide band-gap semiconductors, CdTe and Cd(Zn)Te. On that knowledge basis, solid-state detectors of ionizing radiation were generated that operate at room temperature. One of their most important parameters is their energy resolution that is determined by the quality of the charge collection occurring during the absorption of gamma rays. Numerous studies specifically have aimed at bettering the charge collection. One way to improve the non-equilibrium charge carrier collection (especially of holes) is to increase the strength of the electric field. In this case, the competing limiting factor is the concurrent enhancement of the detector’s leakage current that eventually increases the noise beyond a reasonable threshold value, and, ultimately, leads to an unacceptable deterioration in the detector’s energy resolution. To reduce leakage current, several methods can be used that particularly are applicable to the so-called homogenous detectors (i.e., those with ohmic contacts). These methods include annealing the detector with already established contacts [1], various methods of passivating its lateral surfaces [2-4], and, cooling of the detector via thermoelectric elements. Often an increase in a detector’s dark current is associated with leakage along its lateral surfaces, while a decline in the leakage current is connected with passivation of its side surfaces [3, 4]. Our studies of this