History of ZnO Growth by CVD Process

The reactions with N2O and CO2 lead to growth rates that are much lower than those obtained when using O2 or H2O. On the other hand, the high reactivity of O2 and H2O with DEZ and DMZ can induce premature reactions that may cause difficulties in controlling the deposition of ZnO layers. This aspect became especially important when deposition on large substrates was considered. To overcome this problem, less reactive agents have also been used, like tetrahydrofuran and alcohols. 

The CVD process was carried out hrst at Atmospheric Pressure (AP-CVD), as illustrated by the typical schematic diagram shown in Fig. 6.1. Later on, the pressure was reduced to 0.1-10Torr, in order to improve further the control of the chemical reactions involved in the deposition process, and thus, also improve the thickness homogeneity of the resulting layers [2,4,9,16-18]. A further advantage of the low-pressure CVD (LP-CVD) process is that the 

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