Remarkable breakdown voltage enhancement in AlGaN channel high electron mobility transistors

Abstract

The channel layer substitution of a wider bandgap AlGaN for a conventional GaN in high electron mobility transistors (HEMTs) is an effective method of enhancing the breakdown voltage. We demonstrated a remarkable breakdown voltage enhancement in these AlGaN channel HEMTs. The obtained maximum breakdown voltages were 463 and 1650V in the Al0.53Ga0.47N∕Al0.38Ga0.62N HEMT with the gate-drain distances of 3 and 10μm, respectively. This result is very promising for the further higher power operation of high-frequency HEMTs.

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…For AlGaN with 40-60% Al content, specific contact resistivities are typically in the 10 −2 to 10 −1 Ω cm 2 range, while by contrast Ohmic contacts to conventional WBG AlGaN/ GaN HEMTs are routinely in the 10 −6 Ω cm 2 range. [336,337] Exotic metallizations, such as vanadium, have been reported to have specific contact resistivity in the 10 −6 Ω cm 2 range for AlGaN up to 70% Al composition, but the resistivity rapidly increases for still-higher Al compositions, peaking around 100 Ω cm 2 for AlN.…”

High Temperature Operation of Al0.45Ga0.55N/Al0.30Ga0.70N High Electron Mobility Transistors

“…In addition, the HEMTs compare favorably in current density to previous results at a comparable channel composition that is slightly higher at x = 0.38, but also has a slightly more negative V th . 8 Also, the HEMTs of this study all display I-V curves that are strictly linear through the origin, evidence of true ohmic behavior for the source and drain contacts over all temperatures. Such contacts are progressively more difficult to achieve without rectifying behavior as the Al-channel composition is increased.…”

“…Previously published characteristics of AlGaN-channel HEMTs begin to lend support to these motivations. [8][9][10][11][12][13] In particular, the saturation drain current is reported to be relatively insensitive to temperature in AlGaN-channel HEMTs 9 and very favorable low leakage Schottky gate properties with very high drain current on-to-off ratios have been reported as well.13 * Electrochemical Society Member. z E-mail: agbaca@sandia.gov…”

Development of 2" AlN Substrates Using SiC Seeds

“…Studies of high-electron mobility transistors (HEMTs) with the ALGaN channel 7 grown on different substrates also demonstrate the superiority of the single crystal AlN substrates (Hu et al, 2003), in particularity, the use of AlN substrates improved the crystalline quality of the AlGaN layer and lowered the sheet resistance of the 2-dimensional electron gas (Hashimoto et al, 2010). The substrates cut from the bulk crystals along the specific crystallographic plane can have different orientation (polar, semipolar or nonpolar) (Lu et al, 2008) 8 , enhancing the freedom of the device design (Mymrin et al, 2005;Schowalter et al, 2006;Stutzmann et al, 2001): an engineer, using the spontaneous and piezoelectric polarization that is a nonlinear function of the strain and the composition of nitride materials, can tailor the surface and interface charges 7 The channel layer substitution of a wider bandgap AlGaN for a conventional GaN in high electron mobility transistors is an effective method of drastically enhancing the breakdown voltage (Nanjo et al, 2008). 8 For a long time attempts to grow the nitride epitaxial layers on the nonpolar planes were unsuccessful producing the low quality films (Karpov, 2009).…”