Effect of annealing on the optical and photoelectrical properties of Cd x Hg1 − x Te heteroepitaxial structures for the middle infrared range

Optical properties of molecular beam epitaxy‐grown HgCdTe structures with potential wells

“…The narrow lower-energy peak 2 (~5 meV from the BB-type peak at 5 K) was probably related to the luminescence of excitons bound to a shallow acceptor, while peak 1 with the lowest energy was due to transitions "conduction band-acceptor". This kind of PL behaviour is well known for MCT [10], and the appearance of acceptorrelated peaks after annealing in He atmosphere is caused by generation of Hg vacancies, which are acceptors [9]. The intensity of the PL at T<200 K after the annealing increased, which confirms our earlier conclusions on profitable effect of thermal annealing on optical properties of MBE-grown MCT films [9].…”

“…This kind of PL behaviour is well known for MCT [10], and the appearance of acceptorrelated peaks after annealing in He atmosphere is caused by generation of Hg vacancies, which are acceptors [9]. The intensity of the PL at T<200 K after the annealing increased, which confirms our earlier conclusions on profitable effect of thermal annealing on optical properties of MBE-grown MCT films [9]. At 300 K, the shape of the PL band of the annealed samples was similar to that of the asgrown samples, and the PL intensity of the annealed structures increased insignificantly.…”

“…The latter emerged in the spectra at T > 200 K (not shown in Fig. 3), and were probably caused by recombination in other parts of heterostructures [9]. The room-temperature spectra of structures #3 and #11 (both as-grown and annealed) contained one peak (see Fig.…”

Effect of alloy disorder on photoluminescence in HgCdTe

“…After annealing, the PL lines narrows, the corresponding FWHM being about w Hg = 16 meV and w He = 18 meV, respectively. We have observed a similar effect in samples with x ≈ 0.3-0.4 [12]. Figure 4 shows the temperature dependences of δE = E g − E PL for the samples with the spectra shown in Fig.…”

“…As can be seen, the annealing leads, first of all, to a blue shift of the PL line with E Hg = 28 meV and E He = 37 meV, respectively. This effect can be attributed to a certain increase of x due to diffusion of the solid solution components in a non-uniform structure (relative to composition) and due to out-diffusion of Hg for the case of annealing in the He atmosphere [12,13]. This effect can be accounted for by measuring the photo-absorption edge at the room temperature [12].…”