Polarization-Induced GaN-on-Insulator E/D Mode p-Channel Heterostructure FETs

• Published in: IEEE electron device letters 2013-07, Vol.34 (7), p.852-854
• Main Authors: Li, Guowang, Jena, Debdeep, Wang, Ronghua, Song, Bo, Verma, Jai, Cao, Yu, Ganguly, Satyaki, Verma, Amit, Guo, Jia, Xing, Huili Grace
• Format: Article
• Language: English
• Subjects: AlN; Aluminum nitride; Applied sciences; Compound structure devices; Electronics; enhancement and depletion (E/D) mode; Exact sciences and technology; Gallium nitride; GaN; HEMTs; III-V semiconductor materials; Interfaces; Logic gates; Microelectronic fabrication (materials and surfaces technology); MODFETs; Molecular beam epitaxial growth; molecular beam epitaxy (MBE); p-channel; polarization; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; transistor; Transistors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2013.2264311

Polarization-induced p-type doping is realized in molecular beam epitaxy (MBE) grown ultrathin body GaN/AlN heterostructures. The novel heterostructure consisting of a thin strained GaN layer grown on an AlN template exhibits a hole gas density close to the interface polarization charge (~5 × 10 13 /cm 2 ). Both enhancement- and depletion-mode (E/D) p-channel heterostructure field effect transistor (HFETs) are demonstrated. Driven by the high hole density, a 2.4-μm-long D-mode HFET with alloyed ohmic contacts shows improvement of drain current from 150 mA/mm (V GS = 12 V, V DS = 30 V) at 300 K to 270 mA/mm (V GS = 15 V, V DS = 30 V) at 77 K. The extrinsic peak transconductance of the D-mode device increases from 11 mS/mm (V GS = 6 V, V DS = 30 V) at 300 K to 16 mS/mm (V GS = 4 V, V DS = 30 V) at 77 K. Both the drive current and transconductance are recorded in nitride p-channel FETs. MBE regrown heavily Mg-doped p+-GaN is then employed for ohmic contacts of E-mode p-channel HFETs. A 2-μm-long E-mode device with a drain current of 4 mA/mm (V GS = 10 V, V DS = 80 V) and ON/OFF current ratio of 10 3 is achieved.