Reactive ion etching of AlN, AlGaN, and GaN using BCl{sub 3}

The III-V nitrides are promising materials for use in UV-blue-green optoelectronics, high-temperature electronics, and negative-electron-affinity (NEA) electron emitter applications. In order to realize this potential, it is important to develop an etching technology for device fabrication. The stability of the III-V nitrides to harsh chemical environments makes most wet etching extremely difficult, so that dry etching alternatives are desirable. Recent experiments have shown that BCl{sub 3}-based chemistries are effective for reactive ion etching of GaN and that KOH-based solutions may preferentially etch AlN from GaN. This paper reports on the use of BCl{sub 3} for etching AlN and AlGaN in addition to GaN and the creation of structures such as mesas and lines. It also examines the potential use of potassium Hydroxide (KOH) as a wet etchant of the nitrides. AlN, AlGaN, and GaN films grown by either metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) were patterned with Ni in 250 {micro}m x 250 {micro}m squares and 5 {micro}m wide lines to create mesas and lines for typical light emitting diode (LED) or laser diode applications. Reactive ion etching was performed in a commercial reactor using BCl{sub 3} pressures ranging from 5 to 30 mTorr. Subsequent wetmore » etching of these lines showed that KOH-based solutions such as AZ400K developer attack not only AlN but also GaN depending upon the quality of the film. Possibilities for using this wet etch as a defect etchant or selective etch of nitrides on SiC are discussed.« less