Study of interface traps from transient photoconductive decay measurements in passivated HgCdTe

Abstract

Generation-recombination (g-r) processes in the passivant/HgCdTe interface region are shown to complicate the transient photoconductive (PC) decays. Anomalous PC decays showing delayed peaks are observed and modeled for the first time. These peaks are correlated with the electron and hole traps in the interface region. Activation energy and density of the electron traps in the anodic oxide/n-Hg 0.78 Cd 0.22 Te interface region are estimated to be 12 meV and 1.1 × 10 10 cm -2 , respectively. Density of hole traps is estimated to be 2.4 × 10 10 cm -2 .

Fundamental materials studies of undoped, In-doped, and As-doped Hg1−xCdxTe

“…Similar behavior has been reported previously in HgCdTe and interpreted in terms of trapping effects on the recombination kinetics. 24 The As dopants introduced during the MBE growth tend to occupy the Hg sublattice, to form As Hg . An activation anneal shifts most of the As to the desired Te sublattice, As Te , although the reaction also creates such byproducts as Te I , Te Hg , Te Hg -V Hg complexes, and As-related defects.…”

Study of the traps at a mercury cadmium telluride–anodic oxide interface using a transient photoconductive decay technique

“…(1) cannot account for the appearance of peaks observed in the PC decay measurements at higher bias currents. In a previous paper [7], we have attributed these peaks to the capture of photo-generated carriers in the interface traps, followed by their emission from the traps. The whole phenomenon of capture and emission of the carriers by the traps was treated as equivalent to the charging and discharging of a capacitor, and the conductance of the sample was assumed to be the sum of two conductances, namely g 1 and g 2 : The latter is the result of trapping and de-trapping of the carriers in the traps.…”

“…The whole phenomenon of capture and emission of the carriers by the traps was treated as equivalent to the charging and discharging of a capacitor, and the conductance of the sample was assumed to be the sum of two conductances, namely g 1 and g 2 : The latter is the result of trapping and de-trapping of the carriers in the traps. Using these concepts and some mathematical manipulations, the density of the vacant interface traps N T could be related to the time constant t 1 of a RC circuit using the following relation [7]:…”

“…Recently, it has been shown that the usefulness of this technique can be further enhanced to study interface traps by extending the range of measurements to relatively higher bias currents [7]. In the higher bias regime, distinct peaks superimposed over the conventional PC decay curve of the sample are observed.…”

Accurate measurement of composition, carrier concentration, and photoconductive lifetime in Hg1−xCdxTe grown by molecular beam epitaxy

“…Similar behavior has been reported previously in HgCdTe and interpreted in terms of trapping effects on the recombination kinetics. 28 Arsenic dopants introduced during the MBE growth tend to occupy the Hg sublattice, to form As Hg . An activation anneal shifts most of the As to the desired Te sublattice, As Te , although the reaction also creates such byproducts as Te I , Te Hg , Te Hg -V Hg complexes, and As-related defects.…”