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Optical and theoretical investigations of small InP quantum dots in GaxIn1-xP
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Optical and theoretical investigations of small InP quantum dots in GaxIn1-xP

Jonas Persson, Magnus Holm, C Pryor, Dan Hessman, Werner Seifert, Lars Samuelson and Mats-Erik Pistol
Physical review. B, Condensed matter and materials physics, Vol.67(3), 035320
01/15/2003
DOI: 10.1103/PhysRevB.67.035320

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Abstract

We have studied small InP quantum dots in a GaInP matrix theoretically and experimentally. Using low-temperature photoluminescence spectroscopy in conjunction with six band k.p calculations, including direct and exchange interactions, we show that the dot size is a crucial parameter that determines whether the dot is neutral or charged with electrons in the nominally undoped n-type host material. For a small enough quantum dot, the conduction-band ground state is positioned above the Fermi level and the dot remains neutral. However, as soon as the dot is large enough for the conduction-band ground state to be located below the Fermi level the dot is charged. Furthermore, we show that, for neutral quantum dots, the position of the bi-exciton emission line with respect to the exciton emission line depends on the size of the quantum dot and that the bi-exciton emission can be on either side of the exciton emission: for the smallest dots the bi-exciton emission is always at higher energy than the exciton emission but for larger dots the ordering is the opposite with the exciton emission line on the high-energy side.
 Condensed Matter Physics Natural Sciences Physical Sciences Den kondenserade materiens fysik Fysik Naturvetenskap

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