Deep Traps and Parasitic Effects in Al_0.25Ga_0.75N/GaN/SiC Heterostructures with Different Schottky Contact Surfaces

Salah Saadaoui^1,2, Olfa Fathallah¹, Mohamed Mongi Ben Salem¹, Christophe Gaquière³, Hassen Maaref¹

¹Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Monastir, Tunisie.
²Faculty of Sciences and Arts ( Mohail Asir Campus-Males), King Khalid University, Abha, Kingdom of Saudi Arabia.
³Institut d’Electronique de Microélectronique et de Nanotechnologie IEMN, Département Hyperfréquences et Semiconducteurs, Université des Sciences et Technologies de Lille, Villeneuve d’Ascq Cedex, France.

DOI: 10.4236/oalib.1101562                

Abstract

Hysteresis phenomenon in the capacitance-voltage characteristics under reverse-biased Schottky gate has been investigated for Al_0.25Ga_0.75N/GaN/SiC structures having three different gate surfaces. This parasitic effect was correlated with the presence of deep levels in our samples. Indeed, we have noticed the presence of two traps named H1 and A1; their respective activation energies, which are determined using capacitance deep level transient spectroscopy (DLTS) are respectively 0.74 and 0.16 eV. The H1 hole trap was associated to extended defect in the Al_0.25Ga_0.75N/ GaN heterostructure such as threading dislocations and was responsible of capacitance hysteresis phenomenon. The A1 electron trap appears only in the HEMT (1), which has the smaller Schottky contact area. This trap was related to a punctual defect and attributed to free surface states in the access region between the gate and the source.

Keywords

AlGaN/GaN HEMT, Capacitance Hysteresis, Deep Traps, Gate Surface Effect

Conflicts of Interest

The authors declare no conflicts of interest.

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