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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-Vcharacteristics 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 Sisubstrate/AlN-ML heterojunctions pointed out. The I-Vcharacteristic 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.

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