Reduction of carbon proximity effects by including AlGaN back barriers in HEMTs on free‐standing GaN. Issue 14 (1st July 2013)

• Record Type: Journal Article
• Authors: Kaun, S.W.; Wong, M.H.; Lu, J.; Mishra, U.K.; Speck, J.S.
• Is Part Of: Electronics letters. Volume 49:Issue 14(2013)
• Page Start: 893
• Page End: 895
• Publication Date: 2013-07-01
• Subjects: aluminium compounds -- electric breakdown -- gallium compounds -- high electron mobility transistors -- III‐V semiconductors -- molecular beam epitaxial growth -- silicon compounds -- wide band gap semiconductors; carbon proximity effects reduction -- back barriers -- HEMT structures -- high‐electron‐mobility transistor -- molecular beam epitaxy -- GaN‐on‐SiC templates -- FS substrates -- free‐standing substrates -- very low threading dislocation density -- TDD -- high buffer breakdown voltage -- unintentionally doped buffer layer -- UID -- three‐terminal breakdown voltage -- power‐added efficiency -- PAE -- efficiency 37 percent -- frequency 4 GHz -- voltage 40 V -- size 5 nm -- Al0.3Ga0.7N -- SiC; aluminium compounds -- electric breakdown -- gallium compounds -- high electron mobility transistors -- III‐V semiconductors -- molecular beam epitaxial growth -- silicon compounds -- wide band gap semiconductors; carbon proximity effects reduction -- back barriers -- HEMT structures -- high‐electron‐mobility transistor -- molecular beam epitaxy -- GaN‐on‐SiC templates -- FS substrates -- free‐standing substrates -- very low threading dislocation density -- TDD -- high buffer breakdown voltage -- unintentionally doped buffer layer -- UID -- three‐terminal breakdown voltage -- power‐added efficiency -- PAE -- efficiency 37 percent -- frequency 4 GHz -- voltage 40 V -- size 5 nm -- Al0.3Ga0.7N -- SiC; Electronics -- Periodicals; 621.381
• DOI: 10.1049/el.2013.1723
• Languages: English
• ISSNs: 0013-5194

Abstract

Abstract : High‐electron‐mobility transistor (HEMT) structures were regrown by molecular beam epitaxy on GaN‐on‐SiC templates and free‐standing (FS) GaN substrates with very low threading dislocation density (TDD). To ensure a high buffer breakdown voltage, the thickness of the unintentionally doped (UID) GaN buffer layer, d UID, was reduced to 200 nm for the HEMTs regrown on FS GaN. A reduction in TDD entailed an increase in the three‐terminal breakdown voltage for passivated HEMTs. With a low d UID, the proximity effects of the carbon‐doped GaN buffer were evident. A power‐added efficiency (PAE) of 37% and continuous‐wave power output ( P out ) of 4.2 W/mm were measured at 4 GHz with a drain bias of 40 V for a HEMT on FS GaN without a back barrier. By including a 5 nm Al0.3 Ga0.7 N back barrier, PAE and P out improved to 50% and 6.7 W/mm, respectively, at a drain bias of 40 V.