On The Built‐in Spontaneous Electric Field In MOVPE Grown GaN Crystals On Sapphire

The spontaneous electric fields present in GaN crystals are known to substantially influence their physical properties. However, the magnitude of these fields remains unknown, with estimates ranging from hundreds to thousands of kV/cm. We present an experimental evaluation of the built‐in electric fields in MOVPE grown GaN layers on sapphire, by fair‐infrared spectroscopy of shallow donor states. The observation of electric‐field‐allowed forbidden transitions suggests homogeneous electric fields of the order of 1 kV/cm.