Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Ambacher, O.; Smart, J.; Shealy, J. R.; Weimann, Nils; Chu, K.; Murphy, Michael J.; Schaff, William J.; Eastman, L.F.; Dimitrov, R.; Wittmer, L.; Stutzmann, M.; Rieger, W.; Hilsenbeck, J.

doi:10.1063/1.369664

Cited by 2,621 publications

(1,424 citation statements)

References 61 publications

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“…This formation mechanism of 2DEG has been already verified in AlGaN/GaN. 16 We further inference the electrons accumulated in potential will form a 2-D electron gas (2DEG). These electrons will increase mobility in comparison to p-n junctions without ADB structure.…”

Section: Methodsmentioning

confidence: 96%

The ZnO p-n homojunctions modulated by ZnMgO barriers

et al. 2015

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In this paper, we fabricated the ultrathin ZnO p-n homojunctions, which modulated by ZnMgO asymmetrical double barriers (ADB). The ADB p-n homojunctions displays step-like curve in the absorption spectrums, this is the first time that quantum confinement effect has been observed in the absorption spectrums at room temperature (RT). The Hall-effect data confirm there is 2-dimensional electron gas in the interface of the ZnMgO ADB p-n junctions. The quantum confinement effect enhances the hall-mobility μ to 103 cm2V −1s−1 based on the polarity of the films. There was no rectification property in the ZnO homojunctions with thickness of 250nm, however, when the ADB was added in the n-type layer of the homojunctions, it displays a typical Zener diode rectification property in the I-V curve.

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Section: Methodsmentioning

confidence: 96%

The ZnO p-n homojunctions modulated by ZnMgO barriers

et al. 2015

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“…For a fully strained AlGaN layer with an Al mole fraction of 30%, a piezoelectrically induced sheet charge of above 10 13 /cm 2 is expected [3]. The discrepancy between the measured and the expected carrier concentration may arise from relaxation of the Al 0.3 GaN layer or from trapping effects.…”

Section: Device Fabricationmentioning

confidence: 99%

Current limitation after pinch-off in AlGaN/GaN FETs

Dietrich

Wieszt

Vescan

et al. 2000

MRS Internet j. nitride semicond. res.

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Piezoelectric AlGaN/GaN FETs on SiC with high carrier mobility have been fabricated yielding I DS =450 mA/mm and g m =200 mS/mm. In the on-state, under UV-illumination, the devices sustain a drain voltage of V DS =49 V, corresponding to a power dissipation of 26.5 W/mm. On turn-on of the device from the pinch-off state, a significant delay in the drain current build-up is observed. This effect depends on the pinch-off time and the pinch-off voltage and can be removed by either a brief UV-illumination or a V DS >25 V applied in the on-state. The drain current transients are characterized by a relaxation time τ , which is in the order of several hundred seconds. From the temperature dependence of τ , an activation energy of about 280 meV and a capture cross section of 4.4·10 -18 cm 2 were determined. The devices show pronounced persistent photoconductivity (PPC) and the drain current I D is sensitive to illumination.

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“…Hence, such polarization-induced doping can also compensate for the intrinsic potential drop. 33 In our study, the formation of depletion and inversion regions in the conduction band is the sole mechanism responsible for securing equilibrium. Figure 1 illustrates the formation of depletion and inversion regions for an unbiased double-barrier structure, with AlN barriers, and GaN well and cladding layers.…”

Section: A Depletion and Inversion Regionsmentioning

confidence: 99%

Polarization-balanced design of heterostructures: Application to AlN/GaN double-barrier structures

2011

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Inversion and depletion regions generally form at the interfaces between doped leads (cladding layers) and the active region of polar heterostructures like AlN/GaN and other nitride compounds. The band bending in the depletion region sets up a barrier that may seriously impede perpendicular electronic transport. This may ruin the performance of devices such as quantum-cascade lasers and resonant-tunneling diodes. Here we introduce the concepts of polarization balance and polarization-balanced designs: A structure is polarization balanced when the applied bias match the voltage drop arising from spontaneous and piezeolectric fields. Devices designed to operate at this bias have polarization-balanced designs. These concepts offer a systematic approach to avoid the formation of depletion regions. As a test case, we consider the design of AlN/GaN double-barrier structures with AlxGa 1−x N leads. To guide our efforts, we derive a simple relation between the intrinsic voltage drop arising from polar effects, average alloy composition of the active region, and the alloy concentration of the leads. Polarization-balanced designs secure good filling of the ground state for unbiased structures, while for biased structures with efficient emptying of the active region they remove the depletion barriers.

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Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Cited by 2,621 publications

References 61 publications

The ZnO p-n homojunctions modulated by ZnMgO barriers

The ZnO p-n homojunctions modulated by ZnMgO barriers

Current limitation after pinch-off in AlGaN/GaN FETs

Polarization-balanced design of heterostructures: Application to AlN/GaN double-barrier structures

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