Conversion of conductivity type in Cu-doped Hg_0.8Cd_0.2Te crystals under ion beam milling

Abstract

The behaviour of copper dopant in p-Hg 1−x Cd x Te single crystals is analysed for in-diffusion in the samples with heterogeneous distribution of Hg vacancies and for ion beam milling. For the case of low Hg vacancy, p-Hg 1−x Cd x Te (x ∼ 0.2) material, copper is found to diffuse by a relay-race interstitial mechanism at low temperature. When the Cu-doped p-Hg 1−x Cd x Te samples are exposed to ion milling, the p-n conversion of conductivity type occurs in a substantially thick subsurface layer (∼10 µm). Unstable donor centres such as copper in interstitials rapidly relax so that residual donors control the conductivity in a converted layer after several hours. The possible causes of the incomplete p-type reconversion are discussed.

Background donor concentration in HgCdTe

“…This film had p−type conductivity after the growth and was not annealed. As can be seen, the relaxation curve levelled off at~10 15 cm -3 , which puts BDC in MBE MCT/CdZnTe somewhere between MCT/GaAs and MCT/Si. Though it is not clear at this moment, why BDC in MCT/CdZnTe is higher than that in MCT/Si, the value of~10 15 cm -3 , as mentioned above, is sufficient for the majority of the current MCT applications.…”

“…The R H (B) and s(B) dependences were analyzed using Discrete Mobility Spectrum Analysis (DMSA) [15]. The use of DMSA allows for considering the contribution of the ion−damaged n + surface layer in the ion−milled samples, and to study defects in the n−type 'bulk' of the treated sam− ple, thus revealing the material properties in question.…”

“…This means that bulk material should provide a good reference point for assessing BDC in MCT. IM−assisted studies of electrical properties of MCT crystals involved In−doped and crystals doped with Cu (acceptor) [15], Se (isovalency dopant) [18], and Au and Ag (also acceptors) [19]. In As can be seen, n 77 ( f ) values shown in Fig.…”

Properties of arsenic–implanted Hg1-xCdxTe MBE films

“…Electrical parameters of the films were determined with the measurements of the magnetic field dependence of the Hall coefficient R H and conductivity σ at T=77 K. The dependences were analyzed using discrete mobility spectrum analysis (DMSA) method [5]. and E 1 +∆ 1 peaks, which are due to transitions Λ 4,5 → Λ 6 and Λ 6 → Λ 6 , respectively.…”

The study of HgCdTe MBE-grown structure with ion milling

“…During the measurements the samples were kept at liquid N 2 (LN 2 ) temperature. The R H (B) and s(B) dependences were analyzed using discrete mobility spectrum analysis (DMSA), as described elsewhere [4,8,9]. First measurements were performed straight after the milling, with the allowance for the time required for mounting samples on the holders and cooling them down to LN 2 temperature.…”