Reproducibility of growing AlGaN/GaN high-electron-mobility-transistor heterostructures by molecular-beam epitaxy

Tang, H.; Webb, J. B.; Bardwell, J. A.; Rolfe, S.; MacElwee, T.W.

doi:10.1016/s0038-1101(00)00198-2

Cited by 18 publications

(9 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…9 The value of x, as determined from x-ray diffraction, was 0.29 and the AlGaN thickness was 16 nm, the mobility 1016 cm 2 /V s, and the carrier concentration 1.52ϫ10 13 cm Ϫ2 , where the latter two values were measured in the wafer center. 9 The value of x, as determined from x-ray diffraction, was 0.29 and the AlGaN thickness was 16 nm, the mobility 1016 cm 2 /V s, and the carrier concentration 1.52ϫ10 13 cm Ϫ2 , where the latter two values were measured in the wafer center.…”

Section: Methodsmentioning

confidence: 99%

Comparison of two different Ti/Al/Ti/Au ohmic metallization schemes for AlGaN/GaN

Bardwell

Sproule

Liu

et al. 2002

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

Self Cite

View full text Add to dashboard Cite

Two different ohmic metallization schemes for AlGaN/GaN heterostructure field-effect transistor structures are investigated. Each consists of Ti/Al/Ti/Au layers, with the Ti contacting the AlGaN surface, and they differ only in the relative thicknesses of Ti and Al. The ''Cornell'' metallization consists of 20/100/45/55 nm thicknesses, respectively, while the ''NRC'' metallization consists of 30/80/120/55 nm thicknesses for the layers. Thus, the Cornell scheme is much richer in Al. The two schemes were compared on the same AlGaN/GaN growth wafer which, because of nonuniformity, provides a variety of contact resistances in the final annealed devices. The Cornell scheme formed good quality ohmic contacts at short anneal times, but clearly contained excess, unalloyed Al, as it showed visible, gas-evolving corrosion in a cleaning solution consisting of 1:1 HCl:H 2 O. The surface morphology was rough and the edge acuity was relatively poor. Auger depth profiling showed a single, almost uniformly mixed layer. The NRC scheme required a longer anneal time, and the contact resistance remained high for larger grained AlGaN/GaN material. It was stable in the HCl:H 2 O cleaning solution, and exhibited good edge acuity and a smooth surface morphology. Auger electron depth profiling of the NRC scheme showed two layers present in the annealed metal. The Auger results are consistent with transmission electron microscope results presented elsewhere. The results suggest that the Cornell scheme would be the choice for materials that are more difficult to contact.

show abstract

Section: Methodsmentioning

confidence: 99%

Comparison of two different Ti/Al/Ti/Au ohmic metallization schemes for AlGaN/GaN

Bardwell

Sproule

Liu

et al. 2002

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

Self Cite

View full text Add to dashboard Cite

show abstract

“…24 Historically, in the authors' laboratory, a growth regime using a high temperature ͑840-880°C͒ just below the GaN thermal decomposition threshold point and a moderate ammonia flux ͑100 SCCM, BEP= 5 ϫ 10 −5 Torr͒ has been established and applied for GaN high-electron-mobility transistors ͑HEMT͒ devices on sapphire and SiC substrates. 25,26 In this growth regime, the growth is via a three-dimensional ͑3D͒ mode, yielding facetted surface morphology but also large grain size, low defect density, and high electron mobility, mainly due to the higher growth temperature used. 25 Unintentionally doped GaN grown in this regime is always n-type conducting.…”

Section: Ammonia Cracking Kinetics and Growth Regimesmentioning

confidence: 99%

Growth kinetics and electronic properties of unintentionally doped semi-insulating GaN on SiC and high-resistivity GaN on sapphire grown by ammonia molecular-beam epitaxy

Tang

Fang

Rolfe

et al. 2010

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

Growth kinetics and electronic properties of unintentionally doped semi-insulating GaN on SiC and high-resistivityGrowth of unintentionally doped ͑UID͒ semi-insulating GaN on SiC and highly resistive GaN on sapphire using the ammonia molecular-beam epitaxy technique is reported. The semi-insulating UID GaN on SiC shows room temperature ͑RT͒ resistivity of 10 11 ⍀ cm and well defined activation energy of 1.0 eV. The balance of compensation of unintentional donors and acceptors is such that the Fermi level is lowered to midgap, and controlled by a 1.0 eV deep level defect, which is thought to be related to the nitrogen antisite N Ga , similar to the "EL2" center ͑arsenic antisite͒ in unintentionally doped semi-insulating GaAs. The highly resistive GaN on sapphire shows RT resistivity in range of 10 6 -10 9 ⍀ cm and activation energy varying from 0.25 to 0.9 eV. In this case, the compensation of shallow donors is incomplete, and the Fermi level is controlled by levels shallower than the 1.0 eV deep centers. The growth mechanisms for the resistive UID GaN materials were investigated by experimental studies of the surface kinetics during growth. The required growth regime involves a moderate growth temperature range of 740-780°C, and a high ammonia flux ͑beam equivalent pressure of 1 ϫ 10 −4 Torr͒, which ensures supersaturated coverage of surface adsorption sites with NH x radicals. Such highly nitrogen rich growth conditions lead to two-dimensional layer by layer growth and reduced oxygen incorporation.

show abstract

“…Given the wide choices of growth parameters, various growth regimes have been utilized by different research groups depending on the applications and substrate types. Historically, in the authors' laboratory, a high temperature and moderate ammonia flux growth regime has been established and applied for an extensive development of GaN HEMT devices on sapphire substrate [3]. In this growth regime, the growth is via a 3-D mode, as indicated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of ammonia—MBE growth of GaN on SiC for transport devices

Tang¹,

Rolfe²,

Sèmond³

et al. 2009

Journal of Crystal Growth

Self Cite

View full text Add to dashboard Cite

Reproducibility of growing AlGaN/GaN high-electron-mobility-transistor heterostructures by molecular-beam epitaxy

Cited by 18 publications

References 17 publications

Comparison of two different Ti/Al/Ti/Au ohmic metallization schemes for AlGaN/GaN

Comparison of two different Ti/Al/Ti/Au ohmic metallization schemes for AlGaN/GaN

Growth kinetics and electronic properties of unintentionally doped semi-insulating GaN on SiC and high-resistivity GaN on sapphire grown by ammonia molecular-beam epitaxy

Mechanisms of ammonia—MBE growth of GaN on SiC for transport devices

Contact Info

Product

Resources

About