Effects of ordering and alloy phase separation on the optical emission characteristics of In1−xGaxAsyP1−y layers grown on GaAs substrates

Abstract

We investigated the optical emission characteristics of low- and high-arsenic content In1−xGaxAsyP1−y alloys grown on exact-oriented (100) GaAs substrates. Clear evidence of a spontaneously ordering superlattice, even in high-arsenic content quaternary samples, was obtained by synchrotron x-ray diffractometry. Photoluminescence measurements at low temperatures revealed the presence of two well-resolved emission bands: an excitation intensity dependent (low-energy) and an excitation intensity independent (high-energy) transitions. Temperature dependent photoluminescence experiments give qualitative information about localization effects of photoexcited carriers in these samples. The origin of carrier localization is attributed to band gap fluctuations in the real space as a result of alloy phase separation and a distribution of domains with varying size and ordering degree.

Analysis of polarized photoluminescence emission of ordered III–V semiconductor quaternary alloys

“…If the same set of diagonal planes is involved, the polarization patterns of the PL emission from the two edge planes of the structure will be distinct, as it was observed on Sample 1. On the contrary, if the ordering in group III and V sublattices occurs in different sets of diagonal planes, such as the set of [ À 111] and [1][2][3][4][5][6][7][8][9][10][11] planes, the PL polarization pattern from the surface, due to the ordering within both sublattices, will be oriented on the same direction, and the PL polarization degree will increase proportionally to the polarizations caused by each one of the ordered sublattices. However, the orientation of the PL polarization patterns from the edge planes will not be along the same direction and the sum of these PL intensities will be similar to that observed on Sample 3.…”

“…The polarization angular dependence of the PL emission of the epitaxial layer, propagating along one of three different crystallographic directions, [001] (from the surface), [1][2][3][4][5][6][7][8][9][10] and [110] (from the edge planes), were measured on three different epitaxial quaternary layers. The measured polarization patterns were compared with the normalized calculated curves.…”

“…The same phenomenon occurs in MOVPE-grown III-V quaternary semiconductor alloys [6][7][8]. Two different types of III-V semiconductor quaternary alloys can be prepared.…”

Barrier-induced carrier localization effects in ordered/disordered/ordered quaternary quantum wells grown onGaAssubstrates

“…[2][3][4] In the case of quaternary quantum well ͑QQW͒ structures grown on GaAs substrates both the barrier and the well layer materials may exhibit distinct ordering degrees. [5][6][7] Anomalous photoluminescence ͑PL͒ emission bands from partially ordered ternary and quaternary alloy layers grown on GaAs substrates have been previously reported. [6][7][8][9] The emission characteristics of these bands are strongly dependent on the growth conditions and substrate orientation.…”

Metalorganic vapor phase epitaxy growth of AlxIn1-xP alloys and its CuPt type atomic ordering

“…On the other hand, the PL peak of the as grown AlInP sample which was with CuPt-B atomic ordered lattice structure showed a clear blue-shift when the measurement temperature was increased within the studied range. This abnormality of the PL emission peak shift suggests carrier (exciton) localization effects, 51,52,53 indicating a spatially indirect recombination of the carriers at the boundaries of domains in the CuPt-B ordered AlInP epilayer. With an increase of the temperature the localized carriers gain enough thermal energy to overcome the barriers between the boundaries of the microscopic domains and the high-energy states become thermally populated at higher temperature, leading to a blue-shift of the transition energy.…”