Effects of Piezoelectric Fields in GaInN/GaN and GaN/AlGaN Heterostructures and Quantum Wells

Im, Jin Seo; Kollmer, H.; Off, J.; Sohmer, A.; Scholz, F.; Hangleiter, A.

doi:10.1557/proc-482-513

Cited by 84 publications

(114 citation statements)

References 9 publications

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“…6 shows that the field is in the 400-600 kV/cm range. This is in agreement with the results of other authors, who also studied AlGaN/GaN heterostructures with similar barrier compositions [5][6][7][8]12]. Second, as exemplified in Fig.…”

Section: Resultssupporting

confidence: 92%

“…However, there is still only a few reports on the physical properties of nitride QWs compared to what is known about the prototypical system AlGaAs/GaAs. This is especially the case when considering the AlGaN/GaN QWs [2][3][4][5][6][7][8] though they appear very promising for extending the applications of nitrides to the far UV spectral region owing to the large direct band gap of AlN (6.2 eV/200 nm). It has been already shown that a large internal electric field of several hundred kV/cm takes place in the wurtzite AlGaN/GaN QWs [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optical and Structural Properties of AlGaN/GaN Quantum Wells Grown by Molecular Beam Epitaxy

Grandjean

Massies

Leroux

et al. 1999

MRS Internet j. nitride semicond. res.

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AlGaN/GaN quantum well (QWs) were grown on (0001) sapphire substrates by molecular beam epitaxy (MBE) using ammonia as nitrogen precursor. The Al composition in the barriers was varied between 8 and 27 % and the well thickness from 4 to 17 monolayers (MLs, 1ML = 2.59Å). X-ray diffraction (XRD) experiments are used to investigate the strain state of both the well and the barriers. The QW transition energy are measured by low temperature photoluminescence (PL). A large quantum confined Stark effect is observed leading to QW luminescence much lower than the emission line of the GaN buffer layer for well width above a certain critical thickness. The built-in electric field responsible for such a phenomenon is deduced from fit of the PL data. Its magnitude is of several hundred kV/cm and increases linearly with the Al composition.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Optical and Structural Properties of AlGaN/GaN Quantum Wells Grown by Molecular Beam Epitaxy

Grandjean

Massies

Leroux

et al. 1999

MRS Internet j. nitride semicond. res.

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“…The B coefficient is also dependent on injection due to the skewed band edges in the active region of LEDs and also on the total number of states that are available. In biaxially strained InGaN/GaN layers, the mismatch strain induces a polarization field (caused by the lack of centro-symmetry in wurtzite lattice) along the growth direction in layers grown on the basal plane [88]. In LEDs based on DHs, this strain-induced piezoelectric field and spontaneous polarization field skew the potential profile, resulting in triangular potential profiles near the hetero-interfaces of active regions.…”

Section: Injection-dependent Radiative Recombination Coefficient (B) mentioning

confidence: 99%

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Avrutin¹,

Hafiz²,

Zhang³

et al. 2014

Turk J Phys

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Abstract:What has turned into highly complex and somewhat misunderstood efficiency loss mechanisms occurring in light-emitting diodes (LEDs) based on the InN-GaN material system at high injection levels are discussed. Suggestions are made as to the dominant mechanism(s) in an open forum format as well as pointing out some of the shortcomings of the methodologies used and premises forwarded. It is unequivocally known that increased junction temperature would cause a reduction in radiative power due to mainly the reduction in radiative recombination efficiency. Another obvious mechanism is the asymmetry in doping in wide bandgap semiconductors, such as GaN, wherein the hole concentration lags well behind that of electrons in the active region. Because an electron and a hole are required for radiative recombination, the radiative efficiency cannot keep up with increasing carrier injection due to progressively lagging hole population. This results in either electron escape without radiative recombination or electron accumulation, which in turn changes the internal bias of the device, manifested as reduced internal forward bias, which reduces the rate of increase in light intensity.Some of the reports ascribe the efficiency loss at high injection levels to Auger recombination (mainly through indirect and recently reportedly direct deductions) as the main and or the only source of efficiency loss by in many cases simply relying on the temperature and injection independent (not well taken) A, B, C coefficients to fit a third order polynomial to the efficiency vs. injection current. As for the direct deduction, the spectroscopic analysis of Auger kicked hot electrons as they traverse through the Γ and L bands before being emitted into the vacuum by means of cesiated surface challenges the existing theories and some experiments regarding carrier scattering and Γ -L separation. Despite just a few reports to the contrary, the bulk of the resonant optical emission experiments do not support the Auger argument as being the main cause. In parallel, there exists a body of theoretical and experimental reports for electron overflow of ballistic/quasi-ballistic electrons traversing the active region to p-GaN, escaping recombination altogether in the active region. In fact and from the get go, the LED industry ubiquitously employed, and continues to do so, an (Al,In)GaN electron-blocking layer (EBL) to prevent electron escape for improved light output that in and of itself would more than suggest that the electron escape (overflow) does indeed occur. The only adverse effect of EBL is * Correspondence: vavrutin@vcu.edu 269 AVRUTIN et al./Turk J Phys that it impedes hole injection due to the valence band offset between the p-type (Al,In)GaN EBL and p-GaN and also generates piezoelectric (if not lattice matched) and differential spontaneous polarization induced fields that pull down the conduction band edge at the interface reducing EBL's effectiveness. To at least reduce the aforementioned aggravating factors to some extent, the ele...

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“…For GaN/Al 0.15 Ga 0.85 N a field of 0.46 MV/cm was calculated while measurements employing photoluminescence resulted in a value of 0.42 MV/cm. 6 The electric field is given approximately by EϭϪ18.6 MV/cm x(Ϫ3.0 MV/cm x) for In x Ga (1Ϫx) N/GaN ͓GaN/Al x Ga (1Ϫx) N͔. The negative sign indicates an electric field in the ͓000-1͔ direction.…”

Section: Basics Of Piezoelectricitymentioning

confidence: 99%

“…The strain induced electric field tilts the conduction and valence bands within the well, resulting in charge separation and increased recombination times as well as a redshift in the emission verse absorption spectrum. [5][6][7] In the last few years, substantial improvement in the structural and electronic properties of GaN has been achieved. This has resulted in major advances in blue-green light-emitting diodes and lasers as well as HFET power devices.…”

mentioning

confidence: 99%

Piezoelectric fields in nitride devices

Beach¹,

McGill²

1999

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

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We have calculated the piezoelectric field and charge distribution for various III-nitride heterostructures. Our calculations include strain energy minimization and doping effects, and are presented to show the magnitude of piezoelectric effects in strained layers. We compare our calculated results to device results where available. These include the two-dimensional electron gas in heterojunction field effect transistors, Schottky diodes with strained layers for Schottky height engineering, and III-nitride single quantum wells. Calculations that included energy considerations resulted in good agreement between predicted and observed field and charge distributions for the heterojunction fields-effect transistors structure.

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Effects of Piezoelectric Fields in GaInN/GaN and GaN/AlGaN Heterostructures and Quantum Wells

Cited by 84 publications

References 9 publications

Optical and Structural Properties of AlGaN/GaN Quantum Wells Grown by Molecular Beam Epitaxy

Optical and Structural Properties of AlGaN/GaN Quantum Wells Grown by Molecular Beam Epitaxy

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Piezoelectric fields in nitride devices

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