The effect of ammonia flow in the AlN spacer on the electrical properties of InAlN/AlN/GaN HEMT structures

✍ Scribed by Gamarra, Piero ;Lacam, Cedric ;Magis, Michelle ;Tordjman, Maurice ;Poisson, Marie-Antoinette di Forte

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 452 KB
• Volume: 209
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.201100090

✦ Synopsis

Abstract

During the past few years it has been reported that a thin AlN spacer of few nanometers needs to be inserted in InAlN/GaN high electron mobility transistors (HEMTs) to obtain high 2DEG carrier mobility. This work presents a systematic study of the effects of varying the ammonia flow in the AlN spacer of InAlN/AlN/GaN HEMTs grown by low pressure metalorganic vapour phase epitaxy (LP‐MOVPE). The strain state, the surface roughness and the growth rate of AlN were found to be dependent on the V/III ratio. In addition the ammonia flow in the interlayer has a strong impact on the structural properties of the subsequent InAlN barrier layer and on the electrical properties of the structure. A sheet resistance as low as 327 Ω/□ with a sheet carrier density of 1.5 × 10^13^ cm^−2^ has been obtained at room temperature.