Effects of annealing on Ti Schottky barriers on n-type GaN

Hirsch, M.; Duxstad, K. J.; Häller, E. E.

doi:10.1049/el:19970021

Cited by 32 publications

(31 citation statements)

References 6 publications

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“…The improvements in Schottky properties are due to the intimate Ni/ Au contact with the AlGaN barrier layer by annealing. 6,12 The positive shift in V th ͑−3.57 V to − 3.20 V͒ and the enhancement of g m max by annealing can also be correlated with the improvement in the n and B . Low reverse I g Leak of more than three orders of magnitude was observed at −20 V on the annealed devices compared to the as-fabricated HEMTs ͓Fig.…”

Section: Enhancement Of Both Direct-current and Microwave Characterismentioning

confidence: 95%

Enhancement of both direct-current and microwave characteristics of AlGaN∕GaN high-electron-mobility transistors by furnace annealing

Arulkumaran

Liu

et al. 2006

Applied Physics Letters

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The enhancement of both direct-current (dc) and microwave characteristics of AlGaN∕GaN high-electron-mobility transistors (HEMTs) were demonstrated by conventional furnace annealing at 400°C for 5min. Due to the improvement in Ni∕Au Schottky contact properties by furnace annealing, about 17%, 34%, 23%, and 25% of enhancements in maximum drain current density, maximum extrinsic transconductance (gmmax), cutoff frequency and maximum oscillation frequency were observed, respectively. A positive threshold voltage shift and the increase in gmmax can also be correlated to the improved Schottky parameters such as ideality factor and barrier height. The annealed devices exhibited low reverse gate-leakage-current by more than three orders of magnitude and low drain-leakage-current by two orders of magnitude. Correspondingly, the devices exhibited 55% of higher breakdown voltage after annealing. The furnace annealing is an effective and viable means to enhance both dc and microwave characteristics of AlGaN∕GaN HEMTs.

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Section: Enhancement Of Both Direct-current and Microwave Characterismentioning

confidence: 95%

Enhancement of both direct-current and microwave characteristics of AlGaN∕GaN high-electron-mobility transistors by furnace annealing

Arulkumaran

Liu

et al. 2006

Applied Physics Letters

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“…Much work has been done already to discover the nature of metal/GaN Schottky contacts. [1][2][3][4][5][6][7][8][9][10][11][12] However, most of these works describe the Schottky diode characteristics for only one or two metals, and none encompass more than four metals. Comparisons between works can be misleading due to great differences in the measurement techniques, the GaN epilayer quality, carrier concentration, and surface preparation before metal deposition.…”

Section: Introductionmentioning

confidence: 99%

Metal contacts to n-type GaN

Schmitz

Ping

Khan

et al. 1998

Journal of Elec Materi

177

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Contacts consisting of various single layer metals to n-type GaN have been formed and characterized. The current-voltage characteristics were measured for 17 different metals (Sc, Hf, Zr, Ag, Al, V, Nb, Ti, Cr, W, Mo, Cu, Co, Au, Pd, Ni, and Pt) deposited on the same epitaxial growth layer. The barrier height, ideality factor, breakdown voltage, and effective Richardson coefficients were measured from those metals which exhibited strong rectifying behavior. The barrier heights for these metal contacts were measured using current-voltagetemperature and capacitance-voltage techniques. It was found that an increase in metal work function correlated with an increase in the barrier height. The surface state density of GaN was approximated to be very similar to CdS and almost a factor of ten less than GaAs.

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“…One way that the barrier height could be lowered is by the AlN layer eliminating any Fermi level pinning at the metal/GaN interface. Measured barrier heights of Ti contacts to ntype GaN are higher than the work function difference between Ti and n-type GaN, 9,11 indicating that some pinning occurs. Another possible effect of the interfacial layer is that the potential drop across the AlN would tend to lower the barrier height, as is the case for other metal-insulator-semiconductor structures.…”

Section: Resultsmentioning

confidence: 93%

“…This phenomenon has been reported for Ti contacts annealed at low temperatures. 9 After 40 min at 400°C, the Ta/Al contacts remained rectifying. By AES depth profiling, shown in Fig.…”

Section: Resultsmentioning

confidence: 97%