Schottky Barrier Contacts to GaN

FIGURE 1 Reported Schottky barrier heights of metal contacts to n-GaN [1-19] plotted against the work function of the metal [20], 

Interestingly, the Re/n-GaN diode was recently reported to exhibit a barrier height of 0.82 eV (by I-V measurements at 150°C) and 1.06 eV (by C-V measurements) and did not degrade upon exposure to N2 gas at 700°C for 10 min [17]. Comparable stability of Re/GaN contacts against interfacial reactions has been predicted and observed [30,31], Other diodes with demonstrated thermal stability beyond that of Ni/n-GaN or Pt/n-GaN include Ni/Ga/Ni/n-GaN [25], NiSi/n-GaN [28] and PtSi/n-GaN [22], 

Very little work has been performed on Schottky barrier contacts to the other III-N semiconductors, although a strong dependence of the Schottky barrier height of metal contacts to AIN on the electronegativity of the metal was reported in 1969 [35], 

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Cl. 1 Ohmic contacts to GaN and the III-V nitride semiconductor alloys C1.2 Schottky barrier contacts to GaN Cl.3 Band offsets at interfaces between AIN, GaN and InN... 

Gate formation Schottky gate on GaN channel Metal gate on dielectric insulator (such as Si3N4, AIN) Ohmic contact to p-GaN gate Schottky gate on AlGaN barrier... 

Schottky diode sensors based on other wide bandgap materials have also been investigated, as previously mentioned. GaN Schottky diodes processed on either the Ga or N face have been examined by Schalwig et al. [11,21]. A Pt/GaN Schottky diode with a barrier height of 1-eV has been shown to reversibly transform into an ohmic contact through exposure to [94]. Kokobun et al. have also investigated Pt-GaN Schottky diodes as hydrogen sensors up to 600°C [15]. 

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