Realization of Carrier Tunneling from InAlAs Quantum Dots to AlAs

TL;DR

This paper demonstrates electron tunneling from InAlAs quantum dots through a thin barrier to AlAs, which could enhance the efficiency of quantum dot solar cells by facilitating carrier transfer.

Contribution

It reports the realization of carrier tunneling from InAlAs quantum dots to AlAs using molecular beam epitaxy, with measured tunneling times indicating potential for solar cell improvements.

Findings

Tunneling time decreased to 390 ps with a 2 nm barrier

Photoluminescence decay time reduced from 1.1 ns to 390 ps

Tunneling duration exceeds that of GaAs and InAlAs quantum wells

Abstract

With the aim of improving solar cell efficiency, a structure for realizing electron tunneling from In0.6Al0.4As quantum dots (QDs) through an Al0.4Ga0.6As barrier to AlAs has been grown using molecular beam epitaxy. The photoluminescence decay time decreased from 1.1 ns to 390 ps as the barrier thickness decreased from 4 to 2 nm, which indicates that the photo-excited carriers tunneled from the QDs to the AlAs X energy level for a barrier thickness 2 nm in 0.6 ns, which is significantly longer than the tunneling time of GaAs and InAlAs quantum wells. We expect that this structure will assist in developing high-efficiency QD sensitized solar cells.