Electrical and structural properties of rapidly annealed Pd/Mo Schottky contacts on n-type GaN

Abstract

Electrical and structural properties of palladium/molybdenum (Pd/Mo) Schottky contacts on n-type GaN have been investigated as a function of annealing temperature by current-voltage (I-V), capacitance-voltage (C-V), x-ray diffraction (XRD) and Auger electron spectroscopy (AES) techniques. An as-deposited Pd/Mo/n-GaN Schottky diode exhibits a barrier height of 0.68 eV (I-V) and 0.82 eV (C-V), which increased to 0.75 eV (I-V) and 0.89 eV (C-V) after annealing at 400 • C. However, it is noted that the barrier height slightly decreased to 0.73 eV (I-V) and 0.87 eV (C-V) when the contact was annealed at 500 • C. A maximum barrier height of 0.78 (I-V) and 1.09 eV (C-V) was achieved on the Pd/Mo contacts annealed at 600 • C. The Norde method was also employed to extract the barrier height of Pd/Mo contacts, and the values are 0.70 eV for the as-deposited and 0.82 eV for the contact annealed at 600 • C which are in good agreement with those obtained by the I-V technique. Based on the Auger electron spectroscopy and x-ray diffraction studies, the formation of gallide phases at the Pd/Mo/n-GaN interface could be the reason for the increase of Schottky barrier heights upon annealing at elevated temperatures. The AFM results showed that there was no significant degradation in the surface morphology (rms roughness of 4.61 nm) of the contact even after annealing at 600 • C. These results make Pd/Mo Schottky contacts attractive for high-temperature device applications.

Ti3C2Tx MXene van der Waals Gate Contact for GaN High Electron Mobility Transistors

“…[6,8,15,16] To enhance the gate controllability of Schottky gate GaN HEMTs, high-quality interfaces between metal electrodes and GaN are required. Several 2D and 3D materials have been evaluated as Schottky gate electrodes in GaN HEMTs, such as Cu, [2,17] Pt, [7] Cr, [18] Pb, [17,19] Ir, [19] Mo, [20] ITO, [21,22] TaN, [23] TiN, [3] W, [24,25] WN or WC, [18] TiSi 2 , [11] Au [9] graphene, [10] MoS 2 , [26] and Ni. [27][28][29] However, the most extensively used gate electrode, Ni/Au bilayer film, is not CMOS-compatible.…”

Thermal annealing effect on electrical and structural properties of Tungsten Carbide Schottky contacts on AlGaN/GaN heterostructures

“…However, many Au-free Schottky metallizations for GaN-based heterostructures have been proposed as an alternative, e.g. Ti [16], Cr [16], Pt [17,18], Pd [17,19], Ir [19,20], Mo [21], Pd/Mo [22], TiSi 2 /Cu [23], ITO [24,25], TaN [25,26], and TiN [27,28]. The latter (TaN and TiN) exhibited some interesting features, such as a low leakage current combined with a good thermal stability [26,27].…”

Electrical characteristics and interfacial reactions of rapidly annealed Pt/Ru Schottky contacts on n‐type GaN

“…Many investigations of metallization schemes for the fabrication of Schottky contacts to n‐type GaN have already been reported e.g ., Re 8, Ni/Ta 9, Cu 3 Ge 10, WSi x and W 11, Au 12, Rh/Au 13, Ir/Pt 14, Ni/Rh/Au 15, Pd/Mo 16, Au/Pt/Ti 17, Pt/Mo 18, Ni/Ru 19, Ni 20. Chen et al 9 studied the thermal annealing effects on electrical and interfacial reactions of Ni/Ta/n‐GaN Schottky diodes by current–voltage ( I – V ), X‐ray photoelectron spectroscopy (XPS), and AES techniques.…”

“…They observed that the Ni/Rh/Au contact exhibited better electrical performance, including a higher SBH, a lower leakage current and better thermal stability compared to Rh/Au and Ni/Au contacts. Rajagopal Reddy et al 16 investigated the electrical and structural properties of Pd/Mo Schottky contacts on n‐GaN at different annealing temperatures and showed that the Pd/Mo Schottky contact exhibited better electrical characteristics after annealing at elevated temperatures. Macherzynski et al 17 studied the electrical characteristics of Au/Pt/Ti Schottky contacts to n‐GaN as a function of annealing temperature by the I – V method.…”