Formation of interface layers in GaxIn1−xAs/InP heterostructures: A re-evaluation using ultrathin quantum wells as a probe

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Abstract
We have studied the metalorganic vapor phase epitaxy growth of ultrathin GaInAs/InP and GaAs/InP quantum well (QW) structures using photoluminescence (PL) spectra as a probe for interface effects. In parallel we have also studied InAsxP1−x ‘‘interface QWs’’ formed by simply exposing InP to AsH3. We see a correlation between QW properties (PL peak position, effective thickness, PL half‐width) and the surface phase during the growth of the QW material. For GaAs QWs grown under conditions where typically the As‐excess c(4×4)/d(4×4)‐ or (1×2)‐like (with As double layers) surface reconstructions, we find a strong red‐shift of the PL peak positions. The red‐shift becomes smaller the closer the growth conditions come toward the border to the (2×4) reconstruction (with only one As‐termination layer). We thus conclude that the surface itself is one source for As carryover. For GaInAs QWs a boundary between an As‐excess/no As‐excess surface reconstruction seems to exist at higher AsH3/lower T values. Near to this border GaInAs QWs can be deposited which show PL‐half‐widths between 7 and 11 meV even for the range of 1–5 ML nominal thickness. The P/As replacement reaction at the lower interface is for short AsH3 interaction times (≤1 s) restricted to less than 1 ML and contributes a relatively constant amount to the effective thickness of the QW. Similarly, we show that InAsxP1−x interface QWs formed by short time interaction of InP and AsH3, originate less from a reaction into the depth of the InP, but more from a consumption of the As which is adsorbed onto the InP surface after the AsH3 treatment.