Electrical investigations of AlGaN/AlN structures for LEDs on Si(111)

The carrier transport in AlGaN light emission diode (LED) structures on Si‐substrates including an AlN multilayer (ML) buffer for reduction of defects was investigated using I – V ‐characteristics and admittance spectroscopy. Additionally, AlN on Si ML and AlN/AlGaN:Si on Si structures were grown and analyzed separately. The AlN‐ML/AlGaN:Si heterojunction, and the pn‐junction including the AlGaN/GaN multi quantum well (MQW)‐structure were identified. As the main space charge regions (SCRs) controlling the carrier transport through the ultraviolet‐light emission diode (UV‐LED) structure the Si‐substrate/AlN‐ML heterojunctions pointed out. The I – V ‐characteristic of the LED structure is described by the series resistance of the AlN‐ML and a parallel resistance with respect to the pn‐junction. Interface defect states and/or deep defects impact the series resistance. The carrier transport through the LED structure is controlled by a tunnel process described by a Fowler–Nordheim (FN)‐emission mainly through the AlN‐ML buffer forming the series resistance.