Different GaAs-matched epitaxial structures based on InGaP and
InGaAlP layers were prepared by LP MOVPE. The suitable p- and n-type
sequence of these layers will be used as active elements in high
efficiency solar cells. The layers were grown on (001) GaAs substrates
oriented 2° off towards (110) using trimethylgallium (TMG),
trimethylaluminium
(TMA), trimethylindium (TMI), arsine (AsH3) and phosphine (PH3) as main
reagents and dimethylzinc (DMZ) and silane (SiH4) as p- and n-type
doping reagents, respectively.
The layers have been analyzed as regards their compositional homogeneity,
interface abruptness and doping concentration by different techniques such as
SIMS, TEM and AFM.
The combined analysis of SIMS and TEM has been of great usefulness in order to define the abruptness of composition change. Moreover an analysis of autodoping effects is reported as regards the arsenic diffusion in InGaP matrix and the analysis of different samples is reported.