Analysis of interface states in Pd/n‐ GaN by temperature and frequency dependent admittance

Autor: Azzouz Sellai, M. Mamor
Rok vydání: 2011
Předmět:
Zdroj: physica status solidi c. 8:1611-1615
ISSN: 1610-1642
1862-6351
Popis: Despite the fact that GaN based de-vices are already commercialised, several issues related to the metal-GaN contacts of either ohmic or rectifying (Schottky) nature are still subjects of research studies. One of the key aspects concerns the properties of interfacial layers and interface states known to be a common charac-teristic of semiconductor Schottky contacts especially in compound semiconductors such as the Pd/GaN system. Needless to state the importance of accurately charac-terising these interfaces to better understand the operation of devices with such interfaces and to adequately predict their electrical behaviour and performance. In a recent and relevant study [1], the temperature de-pendence of the current-voltage (I-V) characteristics of Metal/n-GaN Schottky contacts was investigated to reveal a non-ideal behaviour of the Schottky contacts that was at-tributed to the presence of non-uniform distribution of in-terface states, resulting from the residual defects in the as grown GaN. The density of these interface states was ob-tained from the bias and temperature dependence of the ideality factor and the barrier height. Obviously the I-V measurements can only be used to determine the density of the interface states but not their relaxation times or cap-ture-emission rates. One of the most sensitive methods to determine the density of interface states as well as their capture-cross sections is the conductance method [2]. In fact, the exis-tence of interface states is expected to give rise to a dis-placement current within the interfacial layer due to the capture and emission of electrons between the conduction band and traps, which will directly affect the thermionic emission current in these structures. From the measured admittance G + jωC as a function of frequency, bias-voltage and/or temperature, it is possible, following Nicol-lian’s method, to extract the conductance (G
Databáze: OpenAIRE
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