Graphite/CdMnTe Schottky diodes and their electrical characteristics

Abstract

The first Schottky diodes based on n-CdMnTe crystals with pronounced rectifying properties are investigated. It is shown that the I-V characteristics of the diodes fabricated by printing colloidal graphite can be described by the Sah-Noyce-Shockley theory of generation-recombination in the space charge region. Exponential increase of forward current with voltage is limited by a relatively low barrier height at the graphite/CdMnTe contact (∼ 0.4 eV) and a significant series resistance of the crystal bulk (∼ 10 6 at room temperature). Tunneling due to high concentration of uncompensated impurities in investigated Cd 0.9 Mn 0.1 Te crystals (7 × 10 17 cm −3 ) does not allow increasing the reverse bias voltage to the values needed for the operation of x-and γ -ray detectors. High concentration of uncompensated donors is interpreted by the fact that a certain part of the Mn atoms does not substitute for Cd but plays a role of over-stoichiometric impurities. In the case of the presence of a thin intermediate insulator layer in the graphite/CdMnTe contact, a rapid increase in the current for both polarities of high voltage due to the Frenkel-Poole emission is observed. The obtained results shed light on the problems of technology of growing and post-processing CdMnTe crystals regarded as a prospective material for x-and γ -ray detectors.

Growth and characterisation of n- and p-type ZnTe thin films for applications in electronic devices

“…Rectifying diodes fabricated from high resistive semiconductors such as binary compound semiconductors (for example, CdTe, ZnTe) and Ternary compound semiconductors (for example, CdZnTe, CdMnTe) have found useful applications as X-ray and γ-ray detectors [38][39][40][41].…”

CdTe X/γ-ray Detectors with Different Contact Materials

“…Therefore, at high electric fields, the barrier height E t of the trap decreases, leading to the Poole–Frenkel electron emission from the oxide layer [ 50 , 51 ]. Such charge transport mechanism often explains the features of the electrical characteristics of metal-insulator-semiconductor structures [ 47 , 52 ]. The appearance of an oxide layer can occur after chemical polishing etching of the CdTe crystals in a K 2 Cr 2 O 7 + HNO 3 + H 2 O solution and further formation of thin Cd- or Te-rich surface layers [ 53 , 54 ].…”

“…The lowering of the potential barrier height for electrons at the trapping center in high electric field is taken into account by an additional exponential factor exp(−( q 3 V / πεε 0 d i ) 1/2 /kT ), where d i is the thickness of insulator. Therefore, the current can be expressed as [ 51 , 52 ]: …”

“…The square root voltage dependence in the exponent of the last factor is a feature of Poole–Frenkel emission [ 52 ]. As seen, the experimental data on the voltage dependence of the current presented in the corresponding coordinates are linear ( Figure 6 b).…”

Graphite/SiC junctions and their electrical characteristics

“…There is no need for the deposition of a metal contact to measure the I–V characteristics; the graphite was contacted directly by a measuring probe inside a test chamber. Properties of the graphite contact deposited on different semiconductors were studied by several techniques, such as scanning electron microscopy, X‐ray diffraction, Raman spectroscopy, and were presented in our previous papers .…”