SAW characteristics of GaN layers with surfaces exposed by dry etching

Abstract

Abstract:We evaluated the possibility of monolithic integration of electron devices and surface acoustic wave (SAW) devices on GaN. We removed top n+ GaN layers of n+ GaN/unintentionally-doped GaN structures by inductively coupled plasma (ICP) etching and fabricated SAW filters on the exposed unintentionally doped GaN layers. We found that the device characteristics are almost the same as those of devices fabricated on as-grown GaN layers, although the surface morphology of GaN layers is degraded due to the ICP etching. The results indicate that SAW devices and electron devices can be monolithically integrated on GaN-based semiconductor structures. Keywords: GaN, sapphire, surface acoustic wave, SAW, HEMT, monolithic integration Classification: New functional devices and materials References[1] K. Shiojima, T. Makimura, T. Kosugi, S. Sugitani, N. Shigekawa, H.Ishikawa, and T. Egawa, "High-power AlGaN/GaN dual-gate high electron mobility transistor mixers on SiC substrates," Electron. Lett., vol. 40, no. 12, pp. 775-776, June 2004. Kim, "Experimental and theoretical characterization of the surface acoustic wave propagation properties of GaN epitaxial layers on c-plane sapphire,"

SAW Filters Composed of Interdigital Schottky and Ohmic Contacts on AlGaN/GaN Heterostructures

“…The present authors previously discussed the characteristics of SAW devices fabricated on GaN layers exposed by dry etching [11], side-gate effects [12], and excitation of SAWs using n + -GaN-based interdigital transducers (IDTs) [13]. Calle et al [14] reported characteristics of SAW filters made of Ni/Au or Pt/Ti/Au-based IDTs fabricated on AlGaN/GaN heterostructures.…”

Planar Two-dimensional Electron Gas (2DEG) IDT SAW Filter on AlGaN/GaN Heterostructure

“…This integration requires the removal [5] or depletion [6], [7] of two-dimensional electron gas (2DEG) in the heterojunction channel in the SAW device region. The presence of the charge conductivity in 2DEG channel can screen the electric field and prohibit the acousto-electric transductions in the interdigital transducers (IDTs).…”

Surface acoustic wave device on AlGaN∕GaN heterostructure using two-dimensional electron gas interdigital transducers

“…This integration requires the removal 5 or depletion 6,7 of two-dimensional electron gas ͑2DEG͒ in the heterojunction channel in the SAW device region. The presence of the charge conductivity in 2DEG channel can screen the electric field and prohibit the acoustoelectric transductions in the interdigital transducers ͑IDTs͒.…”