Optical property improvement of InAs/GaAs quantum dots grown by hydrogen-plasma-assisted molecular beam epitaxy

Abstract

An order-of-magnitude increase of photoluminescence (PL) efficiency at room temperature has been observed in the GaAs/InAs quantum dots (QDs)-in-a-well structure grown with in situ irradiation of atomic hydrogen supplied by a radio-frequency hydrogen-plasma source. The enhancement in PL intensity rapidly increases with the hydrogen flow rate and is stable with a variation of excitation power in the radio-frequency plasma source. Extensive thermal annealing of grown samples up to 634 °C did not show any significant degradation of photoluminescence intensity compared with the reference sample. The reduction of nonradiative recombination centers in the as-grown sample causes the greatly enhanced luminescence property. In addition to PL enhancement the authors observed that the H-assisted growth of InAs QDs has suppressed bimodal distribution of QD shape. In contrast to the hydrogen-plasma-assisted growth, irradiation by hydrogen in molecular form has a detrimental effect on the optical properties of similar structures. The high thermal stability of improved optical properties suggests that the formation of the defects which are responsible for nonradiative recombination channels is suppressed during H-assisted epitaxy although in situ defect passivation by atomic hydrogen cannot be completely ruled out.

Growth of type II strained layer superlattice, bulk InAs and GaSb materials for minority lifetime characterization

“…surfactant mediated growth and/or to mitigate their effectiveness as recombination centers by e.g. hydrogen exposure during growth, a method that has seen some measure of success in growth of other III-V semiconductor materials [24]. Finally, about the importance of the interface quality, we are not categorically stating that interfaces can have no impact on the SLS lifetimes.…”

Peculiarities of the hydrogenated In(AsN) alloy

“…In spite of the interest in the optimization of the In(AsN) optical properties, the knowledge of the effects hydrogen has on the electronic properties of this semiconductor is still poor, with scattered experimental results. Room temperature PL efficiency increases by an order-of-magnitude in InAs/GaAs quantum dots when irradiated in situ with atomic hydrogen during the growth, while post-growth irradiation with molecular hydrogen has a detrimental effect on PL [31]. On the contrary, post-growth hydrogenation dramatically increases the PL intensity in highly strained, N-free, InAs/GaAs quantum wells [32].…”

Quantum well and quantum dot research at the U.S. Army Research Laboratory (ARL)

“…surfactant mediated growth and/or to mitigate their effectiveness as recombination centers by e.g. hydrogen exposure during growth, a method that has seen some measure of success in growth of other III-V semiconductor materials [22]. Finally, about the importance of the interface quality, we are not categorically stating that interfaces can have no impact on the SLS lifetimes.…”