Defect study in molecular beam epitaxy-grown HgCdTe films with activated and unactivated arsenic

Abstract

A defect study was performed on molecular beam epitaxy-grown HgCdTe films in situ doped with arsenic. Doping was performed from either effusion cell or cracker cell, and studied were both as-grown samples and samples subjected to arsenic activation annealing. Electrical properties of the films were investigated with the use of ion milling as a means of “stirring” defects in the material. As a result of the study, it was confirmed that the most efficient incorporation of electrically active arsenic occurs at the cracking zone temperature of 700 °C. Interaction between arsenic and tellurium during the growth was observed and is discussed in the paper.

Electrical and optical studies of a tellurium‐related defect in molecular‐beam epitaxy‐grown HgCdTe

“…It was experimental facts like these that lead to suggestion that such films contained a neutral defect, a tellurium nanocomplex. After IM, electron concentration n 77 decreases because of disintegration of donor complexes due to decrease in the concentration of interstitial mercury [2][3][4]. This produces 'relaxation' clearly seen for curve 1.…”

“…1. According to the existing concept [3], the electron concentration as measured straight after IM n 77 (i) reflects the total concentration of donors (extrinsic and/or intrinsic donor defects) and donor complexes, which interstitial mercury atoms form with major acceptor impurities and some neutral defects. This is very clearly seen by the example of nominally undoped film М10 (curve 1), where n 77 (i) equals ~10 17 cm -3 with concentration of electrically active impurities in initial (asgrown) sample being lower by two orders of magnitude.…”

“…Also, it was established that these defects did not form in as-grown n-type MBE films that were doped with arsenic with the use of high-temperature cracking. In such films, these defects appeared only as a result of post-growth arsenic activation annealing, which was performed to achieve p-type conductivity [3]. It was suggested that under these growth conditions formation of Te nanocomplexes was prevented because dimeric molecules As 2 in the arsenic flux reacted with excessive Te with formation of donor-type As 2 Те 3 complexes.…”

Длинноволновое стимулированное излучение и времена жизни носителей в волноводных структурах с квантовыми ямами на основе HgCdTe

“…Для получения образцов p-типа необходимо легировать структуру акцепторами. Наиболее привлекательной представляется возможность получить структуры p-типа с помощью легирования мышьяком, однако в этом направлении существует ряд сложностей, несмотря на активные исследования [31]. В настоящее время наиболее часто образцы p-типа получают, используя в качестве акцепторов вакансии ртути.…”

Background donor concentration in HgCdTe

“…It can be noted that with MOCVD technology, vacancy concentration can be reduced far below the equilib− rium level simply by adjusting growth conditions, so the BDC in such material is very important [27]. We studied films grown with MOCVD on CdZnTe and CdTe−buffered semi−insulating (111)B GaAs substrates at VIGO System [28] and with MBE on (311) GaAs [29]. The relaxation of n 77 and μ n77 of two MBE and two MOCVD films with x »0.2 grown on GaAs substrate is shown in figure 8 along with the similar data for an isother− mal vapour phase epitaxy (ISOVPE, yet another vapour− −phase epitaxy method) arsenic−doped film grown on a CdTe substrate at Ivan Franko National University in Lviv, Ukraine [17].…”