Defect Structure Rebuilding by Ion Beam Milling of As and Sb Doped p-Hg1-xCdxTe

Abstract

This study focuses on developing an understanding of the mechanisms of ion beam milling induced p‐to‐n conversion in extrinsically (As or Sb) doped p‐Hg1—xCdxTe with x ≈ 0.2. The basis of modeling is the quasichemical approach and the model of superfast Hg interstitial atoms diffusion that has permitted to explain the similar conversion occurred in Hg vacancy‐doped p‐type Hg1—xCdxTe. In an acceptor doped material a donor is generated due to the formation of a complex (of interstitial Hg atom and an As or Sb atom located in the Te site). This model provides reasonably good fits with the experimental results obtained for As and Sb doped Hg1—xCdxTe epitaxial layers where the electron concentration in the converted n‐layer corresponds to the concentration of the p‐type dopants. Different efficiency of the conductivity conversion observed for As and Sb doped samples may be explained by different enthalpy of complex formation calculated for AsTe–HgI and SbTe–HgI pairs.

Relaxation of electrical properties of n-type layers formed by ion milling in epitaxial HgCdTe doped with V-group acceptors

“…I at H cX > 0.6 eV. The values of H cX were assessed for HgCdTe:As and HgCdTe:Sb as 1 ± 0.1 eV and 0.8 ± 0.2 eV, respectively [10,11]. These estimations mean a high probability of the complex formation under IM.…”

“…Arsenic is currently the most popular acceptor dopant in MCT epitaxial technology due to the low diffusivity of this species [8,9]. Conductivity type conversion in HgCdTe:As subjected to IM was first reported in [4] and was studied in [10][11][12][13][14]. It is commonly accepted now that it takes place through the formation of donor complexes, which comprise an arsenic atom sited in tellurium sublattice As Te , and a mercury interstitial Hg i generated during the milling [10-12, 15, 16].…”

Conversion of conductivity type in Cu-doped Hg0.8Cd0.2Te crystals under ion beam milling

“…Recently the IBM-induced p-n conversion has also been observed in As-doped [7,8], Au-doped [9] or Sb-doped [10] p-MCT samples. Again, in this case the conversion is assumed to result from the diffusion of interstitial Hg and its interaction with the acceptor impurity [8,10,11].…”

“…Recently the IBM-induced p-n conversion has also been observed in As-doped [7,8], Au-doped [9] or Sb-doped [10] p-MCT samples. Again, in this case the conversion is assumed to result from the diffusion of interstitial Hg and its interaction with the acceptor impurity [8,10,11]. It is worth noting that freshly formed complex donors are unstable, which explains the relaxation of characteristics in the converted layer [11,12].…”

Long term relaxation of CdHgTe n+-n–structures formed with ion milling

“…З одного боку, це зумовлює надшвидке просування фронту дифузії (великі глибини) і повну анігіляцію вакансій ртуті (конверсію типу провідності в матеріалі р-типу і модифікацію -зниження рівня компенсації в матеріалі п-типу). З другого боку, висока концентрація ртуті призводить до формування в модифікованому (конвертованому) шарі донорних (комплексів та центрів з найбільш відомими акцепторними домішками в КРТ (As, Sb, Cu, Ag, Au) [6] та певними структурними нейтральними дефектами (передбачається, це нанокомплекси Те) [7]. Нарешті, було встановлено [8] Як видно, після припинення ІТ для всіх зразків спостерігається сильна релаксація концентрації електронів основного об'єму модифікованого nшару залежність n77(t) є експоненціальною.…”