In-depth analysis of the interfaces in InGaP/GaAs heterosystems

¹ IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43010 Loc. Fontanini, Parma, Italy
² ITC-IRST, via Sommarive 18, 38050 Povo, Trento, Italy
³ Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, SK-84239 Bratislava, Slovak Republik

Corresponding author: pelosi@imem.cnr.it

Received: 17 July 2003
Accepted: 15 December 2003
Published online: 15 July 2004

Abstract

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.