Impact of Ge doping on MOVPE grown InGaN layers

The impact of Ge doping on InGaN layers grown with the Metal Organic Vapor Phase Epitaxy technique is investigated, with the main focus on the influence of GeH4 flow and Ga/III ratio on the luminescence, electrical and structural properties of InGaN:Ge layers. It is shown that at doping levels above 1019 cm-3 an increase in GeH4 flow results in a decrease in the In content and lower concentration of free carrier density in InGaN layers. On the contrary, the change of Ga/III ratio has no influence on the luminescence and structural properties. An unintentional Ge doping of InGaN layers due to the Ge memory effect or back diffusion is discussed.