Analysis of in situ reflectance spectra and performance of InGaAs/GaAsP quantum-well solar cells: Towards a comprehensive understanding of strain accumulation influence on solar cell properties

A strain-balanced InGaAs/GaAsP multiple quantum-wells (MQWs) structure was grown with metal organic vapor phase epitaxy (MOVPE) on GaAs substrate towards enhanced current gain by extending adsortion range. In our previous investigation, it has been verified that growth of such a hetero-structure can be diagnosed by periodical oscillation of transient reflectance spectra: an excess amount of strian accumulation (SA) would derive lattice relaxation in MQWs and degrades surface mophology, resulting in a decay in surface reflectance. In this report, we applied a series of detailed in situ monitoring of transient reflectance spectra (RS). According to a combined analysis of transient RS in a course of p-i-n MQWs solar cell growth and spectral response measurement, a comprehensive understanding can be offered to explain SA process through the whole p-i-n hetero-layer, and its influence on solar cell properties.