  Plasma enhanced atomic layer deposition was used to deposit thin films of
Ga2O3 on to c-plane sapphire substrates using triethylgallium and O2 plasma.
The influence of substrate temperature and plasma processing parameters on the
resultant crystallinity and optical properties of the Ga2O3 films were
investigated. The deposition temperature was found to have a significant effect
on the film crystallinity. At temperatures below 200{\deg}C amorphous Ga2O3
films were deposited. Between 250{\deg}C and 350{\deg}C the films became
predominantly {\alpha}-Ga2O3. Above 350{\deg}C the deposited films showed a
mixture of {\alpha}-Ga2O3 and {\epsilon}-Ga2O3 phases. Plasma power and O2 flow
rate were observed to have less influence over the resultant phases present in
the films. However, both parameters could be tuned to alter the strain of the
film. Ultraviolet transmittance measurements on the Ga2O3 films showed that the
bandgaps ranges from 5.0 eV to 5.2 eV with the largest bandgap of 5.2 eV
occurring for the {\alpha}-Ga2O3 phase deposited at 250{\deg}C.
