We present the results of photoluminescence (PL) study of CdTe:Ge substrates, which form part of Hg1-xCdxI2/ CdTe heterostructures grown by low-temperature (< 250degreesC) vapor phase epitaxy (VPE), using a combination of several PL techniques such as spectroscopy, cross-section mapping and profiling. It is demonstrated that the VPE growth causes a simultaneous and interactive transformation of different defect subsystems like native defects, residual impurities and dopants all over CdTe substrate bulk. The dominant processes were found to be the formation of iodine compensating complexes associated with cadmium vacancies and the gettering of defects at layer/substrate interface. (C) 2003 Elsevier B.V. All rights reserved.