Prospects of Ga/In/Al–N Nanometer Devices: Electronic Structure, Scattering Rates, and High Field Transport

Zandler, G.; Majewski, J. A.; Städele, M.; Vogl, P.; Compagnone, F.

doi:10.1002/1521-3951(199711)204:1<133::aid-pssb133>3.0.co;2-e

Cited by 10 publications

(10 citation statements)

References 9 publications

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“…5 It has been recently demonstrated that the large intrinsic piezoelectric coefficients of GaN and AlN are responsible for a high concentration two-dimensional electron gas at the AlGaN/GaN interface in heterojunction field effect transistors ͑HFET͒. 6,7 Other possibilities exist for the enhancement of electric properties of contacts to nitrides by piezoelectric engineering as recently demonstrated in the case of Schottky contacts. 8 While most of the recent research has emphasized electronic device aspects of the piezoelectric effect, [6][7][8] comparatively little work has concentrated on the investigation of fundamental properties and nanoscale characterization of piezoelectrically induced phenomena.…”

Section: ͓S0003-6951͑99͒01223-1͔supporting

confidence: 73%

Measurement of induced surface charges, contact potentials, and surface states in GaN by electric force microscopy

Bridger

Bandić

Piquette

et al. 1999

Applied Physics Letters

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We have studied molecular beam epitaxy grown GaN films of both polarities using electric force microscopy to detect sub 1 m regions of charge density variations associated with GaN extended defects. The large piezoelectric coefficients of GaN together with strain introduced by crystalline imperfections produce variations in piezoelectrically induced electric fields around these defects. The consequent spatial rearrangement of charges can be detected by electrostatic force microscopy and was found to be on the order of the characteristic Debye length for GaN at our dopant concentration. The electric force microscope signal was also found to be a linear function of the contact potential between the metal coating on the tip and GaN. Electrostatic analysis yielded a surface state density of 9.4Ϯ0.5ϫ1010 cm Ϫ2 at an energy of 30 mV above the valence band indicating that the GaN surface is unpinned in this case. © 1999 American Institute of Physics. ͓S0003-6951͑99͒01223-1͔Nitride based devices have been of great interest in the last few years, notably due to their success in optoelectronics, where lasers and diodes have been demonstrated and successfully commercialized.1 Further applications of nitrides are expected in the arena of high power and high temperature devices, 2-4 as well as solar blind ultraviolet detectors.5 It has been recently demonstrated that the large intrinsic piezoelectric coefficients of GaN and AlN are responsible for a high concentration two-dimensional electron gas at the AlGaN/GaN interface in heterojunction field effect transistors ͑HFET͒.6,7 Other possibilities exist for the enhancement of electric properties of contacts to nitrides by piezoelectric engineering as recently demonstrated in the case of Schottky contacts.8 While most of the recent research has emphasized electronic device aspects of the piezoelectric effect, 6-8 comparatively little work has concentrated on the investigation of fundamental properties and nanoscale characterization of piezoelectrically induced phenomena. One consequence of the piezoelectric effect is that it allows electrostatic force imaging of charge redistribution around defects due to local variations in strain caused by crystalline imperfections. Although the magnitude of the charge density is nonquantitative, electric force microscopy ͑EFM͒ can still provide interesting insight into the nature of defects, the piezoelectric effect in nitrides, as well as measurement of the surface state density and energy. 9,10The gallium nitride layers studied here were grown on c-plane sapphire substrates by radio frequency plasma assisted molecular beam epitaxy. Ga-polar GaN films were nucleated using AlN buffer layers whereas N-polar films were nucleated using a GaN buffer layer. Polarity was determined by reflection high-energy electron diffraction ͑RHEED͒ reconstruction at low temperature, 11 and by ͑KOH͒ etching. 12,13 Other details of the growth conditions are presented elsewhere. 14,15 A variety of different metals were used for coating atomic force microscope ͑AF...

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Section: ͓S0003-6951͑99͒01223-1͔supporting

confidence: 73%

Measurement of induced surface charges, contact potentials, and surface states in GaN by electric force microscopy

Bridger

Bandić

Piquette

et al. 1999

Applied Physics Letters

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“…In our Monte Carlo transport calculations, we have used band parameters [12] deduced from the electronic structure calculations described above and have taken into account scattering rates for ionized impurity, intra-and intervalley phonon scattering, acoustic, piezoelectric, polar optical phonon and alloy scattering. The resulting electron drift velocities (see Fig.…”

Section: Bulk Transport Properties Of Gan and Alnmentioning

confidence: 99%

“…To study the influence of polarization fields on device characteristics, we have performed self-consistent two-dimensional Monte Carlo simulations of various nitride based heterostructure devices [12]. At high bias voltages, it suffices to use a bulk description for the hot carrier transport in the channel layers.…”

Section: Influence Of Polarization Fields On Device Performancementioning

confidence: 99%

Novel Nitride Devices Based on Polarization Fields

Majewski

Zandler

Vogl

2000

phys. stat. sol. (a)

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A key property of the nitrides is the fact that they possess large spontaneous and piezoelectric polarization fields that allow a significant tailoring of the carrier dynamics and optical properties of nitride devices. In this paper, based on first-principles calculations of structural and electronic properties of bulk nitrides and their heterostructure, we investigate the potential of this novel material class for modern device applications by performing self-consistent Monte Carlo simulations. We demonstrate that the internal electric fields have a significant and favorable influence on the transistor characteristics.

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“…5 It has been recently demonstrated that the large intrinsic piezoelectric coefficients of GaN and AlN are responsible for an anomalously large concentration of two-dimensional electron gas at the AlGaN/GaN interface in GaN/AlGaN heterojunction field effect transistors ͑HFET͒. 6,7 Other possibilities exist for the enhancement of electric properties of contacts to nitrides by piezoelectric engineering as recently demonstrated in the case of Schottky contacts. 8 While most of the recent research has emphasized electronic device aspects of the piezoelectric effect, [6][7][8] comparatively little work has concentrated on the investigation of fundamental properties and nanoscale characterization of piezoelectrically induced phenomena.…”

Section: Introductionmentioning

confidence: 99%

“…6,7 Other possibilities exist for the enhancement of electric properties of contacts to nitrides by piezoelectric engineering as recently demonstrated in the case of Schottky contacts. 8 While most of the recent research has emphasized electronic device aspects of the piezoelectric effect, [6][7][8] comparatively little work has concentrated on the investigation of fundamental properties and nanoscale characterization of piezoelectrically induced phenomena. One consequence of the piezoelectric effect is that it allows electrostatic force imaging of charge redistribution around defects due to local variations in strain caused by crystalline imperfections.…”

Section: Introductionmentioning

confidence: 99%

Electric force microscopy of induced charges and surface potentials in GaN modified by light and strain

Bridger

Bandić

Piquette

et al. 1999

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

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We have studied molecular beam epitaxy grown GaN films using electric force microscopy to detect sub-1 m regions of electric field gradient and surface potential variations associated with GaN extended defects. The large piezoelectric coefficients of GaN together with strain introduced by crystalline imperfections produce variation in piezoelectrically induced electric fields around these defects. The consequent spatial rearrangement of charges can be detected by electrostatic force microscopy, and can be additionally modified by externally applied strain and illumination. The electron force microscopy signal was found to be a function of the applied tip bias, showed reversal under externally applied strain, and was sensitive to above band gap illumination.

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Prospects of Ga/In/Al–N Nanometer Devices: Electronic Structure, Scattering Rates, and High Field Transport

Cited by 10 publications

References 9 publications

Measurement of induced surface charges, contact potentials, and surface states in GaN by electric force microscopy

Measurement of induced surface charges, contact potentials, and surface states in GaN by electric force microscopy

Novel Nitride Devices Based on Polarization Fields

Electric force microscopy of induced charges and surface potentials in GaN modified by light and strain

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