Elastic strain relaxation and piezoeffect in GaN-AlN, GaN-AlGaN and GaN-InGaN superlattices

Bykhovski, A. D.; Gelmont, Boris; Shur, M. S.

doi:10.1063/1.364368

Cited by 276 publications

(130 citation statements)

References 11 publications

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“…We have previously reported an observation of the 2DEG generated by the strain-induced piezoelectric field in a similar AlGaAs/GaAs/InGaAs system. 12 With a piezoelectric constant two to four times larger than that of GaAs, the strain-induced piezoelectric effect is expected to play a more important role in the formation of 2DEG in the AlGaN/GaN system, 13 with which our experiments exhibit good agreement. For modulation-doped samples, the 2DEG mobility was 753 cm 2 /V s at room temperature and 4070 cm 2 /V s at 77 K. Figure 4 shows the temperature-dependent Hall mobility and sheet carrier density for the modulation-doped sample.…”

Section: ϫ3supporting

confidence: 58%

High mobility AlGaN/GaN heterostructures grown by gas-source molecular beam epitaxy

Li¹,

Alperin²,

Wang³

et al. 1998

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

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We report on the growth of high electron mobility AlGaN/GaN heterostructures on sapphire substrates by gas-source molecular beam epitaxy ͑GSMBE͒ using ammonia as the nitrogen source. Improvements in structural, electrical, and optical properties of GaN and AlGaN layers have been made to achieve this goal. For the growth of AlGaN layers, the reflection high-energy electron diffraction revealed a twofold surface reconstruction, indicative of atomic smoothness of the film surface. High mobility two-dimensional electron gas has been achieved in both unintentionally doped ͑by piezoelectric effect induced by lattice mismatch strain͒ and modulation doped AlGaN/ GaN heterostructures. The modulation-doped nϩ-Al 0.2 Ga 0.8 N/i-GaN heterojunction exhibited electron mobilities as high as 750 and 4070 cm 2 /V s at 300 and 77 K, respectively. Both values are the highest ever reported for the AlGaN/GaN heterostructures grown by MBE techniques.

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Section: ϫ3supporting

confidence: 58%

High mobility AlGaN/GaN heterostructures grown by gas-source molecular beam epitaxy

Li¹,

Alperin²,

Wang³

et al. 1998

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

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“…The difference in lattice parameter might be compensated by introduction of a misfit dislocation every ϳ50 nm in the AlN barrier. These results indicate a critical layer thickness smaller than the ϳ3 nm theoretically predictions by Bykhovski et al 89 The ISB optical properties of the samples grown on different substrates are summarized in Fig. 15 and Table IV.…”

Section: Strain In the Superlattice: Influence Of The Substratementioning

confidence: 74%

GaN/AlN short-period superlattices for intersubband optoelectronics: A systematic study of their epitaxial growth, design, and performance

Kandaswamy¹,

Guillot²,

Bellet‐Amalric³

et al. 2008

Journal of Applied Physics

177

175

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We have studied the effect of growth and design parameters on the performance of Si-doped GaN/AlN multiquantum-well ͑MQW͒ structures for intersubband optoelectronics in the near infrared. The samples under study display infrared absorption in the 1.3-1.9 m wavelength range, originating from the photoexcitation of electrons from the first to the second electronic level in the QWs. A commonly observed feature is the presence of multiple peaks in both intersubband absorption and interband emission spectra, which are attributed to monolayer thickness fluctuations in the quantum wells. These thickness fluctuations are induced by dislocations and eventually by cracks or metal accumulation during growth. The best optical performance is attained in samples synthesized with a moderate Ga excess during the growth of both the GaN QWs and the AlN barriers without growth interruptions. The optical properties are degraded at high growth temperatures ͑Ͼ720°C͒ due to the thermal activation of the AlN etching of GaN. From the point of view of strain, GaN/AlN MQWs evolve rapidly to an equilibrium average lattice parameter, which is independent of the substrate. As a result, we do not observe any significant effect of the underlayers on the optical performance of the MQW structure. The average lattice parameter is different from the expected value from elastic energy minimization, which points out the presence of periodic misfit dislocations in the structure. The structural quality of the samples is independent of Si doping up to 10 20 cm −3 . By contrast, the intersubband absorption spectrum broadens and blueshifts with doping as a result of electron-electron interactions. This behavior is independent of the Si doping location in the structure, either in the QWs or in the barriers. It is found that the magnitude of the intersubband absorption is not directly determined by the Si concentration in the wells. Instead, depending on the Al mole fraction of the cap layer, the internal electric field due to piezoelectric and spontaneous polarization can deplete or induce charge accumulation in the QWs. In fact, this polarization-induced doping can result in a significant and even dominant contribution to the infrared absorption in GaN/AlN MQW structures.

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“…The wurtzite GaN piezoelectric constants were also estimated from the GaN electromechanical coupling coefficients. 17 Finally, the piezoelectric constants of AlN, GaN and InN were predicted using ab initio calculations. 20 These calculations predict that piezoelectric constants in GaN-based materials are up to ten times larger than in other III-V semiconductors.…”

Section: Piezoelectric Properties Of Iii-nitridesmentioning

confidence: 99%

Pyroelectric and Piezoelectric Properties of GaN-Based Materials

Gaška

Shur

Bykhovski

1999

MRS Internet j. nitride semicond. res.

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We review pyroelectric and piezoelectric properties of GaN-based materials. Pyroelectric effects in GaN have been studied in two different regimes: (i) uniform sample heating regime and (ii) under applied temperature gradient along the sample. The modeling results show that the pyroelectric coefficient, P v , in GaN (for c-axis along the contacts) can reach 7x10 5 V/m-K (compared to P v = 5x10 5 V/m-K for the best-known high temperature pyroelectric/piezoelectric material LiTaO 3 ). This points to a high potential of GaN-based sensors for high temperature pyroelectronics. Piezoelectric effects strongly affect the performance of electronic and lightemitting devices based on III-N materials. Piezoelectrically induced charge in heterostructures can be as large as 3 to 4x10 13 cm -2 . Hence, strong lattice polarization effects provide unique possibilities for utilizing GaN-based materials in high temperature piezoelectronics and for their applications in pyroelectric detectors.

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Elastic strain relaxation and piezoeffect in GaN-AlN, GaN-AlGaN and GaN-InGaN superlattices

Cited by 276 publications

References 11 publications

High mobility AlGaN/GaN heterostructures grown by gas-source molecular beam epitaxy

High mobility AlGaN/GaN heterostructures grown by gas-source molecular beam epitaxy

GaN/AlN short-period superlattices for intersubband optoelectronics: A systematic study of their epitaxial growth, design, and performance

Pyroelectric and Piezoelectric Properties of GaN-Based Materials

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