The low temperature epitaxy of Ge on Si (1 0 0) substrate using two different precursors of GeH₄ and Ge₂H₆

We have investigated the initial stage of low temperature epitaxy (LTE) of Ge on 8″-dia. Si (1 0 0) substrate using a rapid thermal chemical vapor deposition (RTCVD) with two different precursors of GeH₄ and Ge₂H₆. The quality of LTE Ge films such as surface morphology, defects and crystallinity were analyzed using SEM, AFM and TEM. Experimental results confirmed that the LTE Ge using Ge₂H₆ precursor was much more beneficial than the LTE using GeH₄ in terms of growth rate (×10), stress relaxation (85% at surface), and crystal quality (low TDDs). The discrepancy looks originated from the weak [Formula presented] bonds requiring their dissociation energy small compared to the [Formula presented] bonds in GeH₄ precursors, and the abundant supply of GeH₃ molecules should stimulate chemical reactions at free surface sites. Our LTE technology would be promising for very thin Ge virtual substrate as well as be beneficial for nano-micro electronic devices in need of low temperature processes below 300–500 °C.