Photoreflectance Studies of AlGaN/GaN Heterostructures Containing a Polarisation Induced 2DEG

Goldhahn, R.; Buchheim, C.; Shokhovets, S.; Gobsch, G.; Ambacher, O.; Link, A.; Hermann, Martin; Stutzmann, M.; Smorchkova, Y.; Mishra, Umesh K.; Speck, James S.

doi:10.1002/1521-3951(200212)234:3<713::aid-pssb713>3.0.co;2-o

Cited by 9 publications

(4 citation statements)

References 10 publications

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“…The investigated temperature range was from low to room temperature. The revealed increase of the built-in electric field was ascribed to the temperature dependence of piezoelectric polarization; − however, this explanation cannot be applied to our study, since sufficient thickness of van Hoof structures screens polarization effects …”

Section: Resultsmentioning

confidence: 78%

Origin of Surface Barrier Temperature Dependence for the Polar GaN Surface

Zdanowicz

Herman

Sobanska

et al. 2022

ACS Appl. Electron. Mater.

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Combining the mature technology of gallium nitride (GaN) with emerging materials such as van der Waals crystals is presently an important path in applied science research. Up to now, a broad spectrum of optoelectronic devices including light emitters, photodetectors, and solar cells based on mentioned materials has been presented. Understanding and controlling the surface-related phenomena is a crucial aspect for proper electrical device operation. In particular, an insight into the impact of external conditions such as elevated temperature on technologically important parameters such as surface barrier is of great importance. In this study we propose the first spectroscopic investigation of the vulnerability of the surface barrier on temperature for the Ga-polar GaN surface. Studies performed in the 300–440 K temperature range using contactless electroreflectance (CER) enabled nondestructive probing of GaN surface states. The range of investigated materials was extended to graphene/GaN and h-BN/GaN hybrids together with GaAs as a reference in order to provide a comprehensive case study. We show that GaN surface densities of states revealed robust temperature dependence compared to the energy gap. The mechanism of temperature-induced carrier redistribution at the surface is proposed as an explanation.

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Section: Resultsmentioning

confidence: 78%

Origin of Surface Barrier Temperature Dependence for the Polar GaN Surface

Zdanowicz

Herman

Sobanska

et al. 2022

ACS Appl. Electron. Mater.

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“…For n 2D = 0.8P , the field in the AlGaN layer is reduced to about 0.4 MV/cm for a Al fraction of 0.3. Evidence for the smaller field is seen in recent photoreflectance (PR) measurements 21,22 on AlGaN/GaN heterostructures in which barrier fields in the vicinity of 0.3 MV/cm were reported for 250 Å thick barriers with Al fractions in the range 0.06 -0.1. An electric field of opposite sign occurs in the GaN layer with similar trends between the coupled and standard models.…”

Section: Resultsmentioning

confidence: 95%

Electromechanical coupling in free-standing AlGaN/GaN planar structures

Jogai

Albrecht

Pan

2003

Journal of Applied Physics

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This work, resulting from Air Force contract F33615-00-C-5402, is copyrighted. The United States has for itself and other acting on its behalf and unlimited, paid-up, nonexclusive, irrevocable worldwide license. Any other form of use is subject to copyright restrictions. MATERIALS AND MANUFACTURING DIRECTORATE AIR FORCE RESEARCH LABORATORY AIR FORCE MATERIEL COMMAND WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7750Approved for public release; distribution is unlimited. /m M./7^N/«M ■m\ ^ »■* u.->«e^ NOTICE Using government drawings, specifications, or other data included in this document for any purpose other than government procurement does not in any way obligate the U.S. Government. The fact that the government formulated or supplied the drawings, specifications, or other data does not license the holder or any other person or corporation; or convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report has been reviewed by the AFRL Wright Site Office of Public Affairs (WS/PA) and is relcasable to the National Technical Information Service (NTIS). At NTIS, it will be available to the general public, including foreign nationals.This technical report has been reviewed and is approved for publication. The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL-ML-WP-TP-2004-403 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES© 2003 American Institute of Physics. This work, resulting from Air Force contract F33615-00-C-5402, is copyrighted. The United States has for itself and other acting on its behalf and unlimited, paid-up, nonexclusive, irrevocable worldwide license. Any other form of use is subject to copyright restrictions. ABSTRACT (Maximum 200 Words), ,The strain and electric fields present in free-standing AlGaN/GaN slabs are examined theoretically within the framework of fully coupled continuum elastic and dielectric models. Simultaneous solutions for the electric field and strain components are obtained by minimizing the electric enthalpy. We apply constraints appropriate to pseudomorphic semiconductor epitaxial layers and obtain closed-form analytic expressions that take into account the wurtzite crystal anisotropy. It is shown that in the absence of free charges, the calculated strain and electric fields are substantially different from those obtained using the standard model without electromechanical coupling. It is also shown, however, that when a two-dimensional electron gas is present at the AlGaN/GaN interface, a condition t...

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“…For all of these applications detailed knowledge of the layer properties is of fundamental importance. Photoreflectance (PR) has been proven a powerful tool for the characterization of such heterostructures [5]. In this work we compare the temperature behaviour of N-and Ga-face samples containing a polarization induced 2DEG with special focus on the electric field strength in the topmost layers.…”

Section: Introductionmentioning

confidence: 99%

“…The setup for the PR measurements has been described elsewhere [5]. Figure 1 shows the PR spectra of the samples B and C taken at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Photoreflectance studiesof N‐ and Ga‐face AlGaN/GaN heterostructures confininga polarisation induced 2DEG

Winzer

Goldhahn

Buchheim

et al. 2003

Physica Status Solidi (b)

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Photoreflectance measurements have been carried out in order to determine the electric field strength F within the topmost layers of Ga‐face polarity AlxGa1−xN/GaN and N‐face polarity GaN/AlxGa1−xN/GaN heterostructures containing high‐mobile polarisation induced 2DEGs. For both types of samples F decreased from 400 kV/cm at room temperature up to 200 kV/cm when cooling down the structure to T = 5 K. Our results strongly emphasise the existence of surface donor and surface acceptor states of the Ga‐ and N‐face samples, respectively. The temperature dependence of F is explained by the change of the piezoelectric and spontaneous polarization. From self‐consistent conduction band calculations the bare surface potential was obtained. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Photoreflectance Studies of AlGaN/GaN Heterostructures Containing a Polarisation Induced 2DEG

Cited by 9 publications

References 10 publications

Origin of Surface Barrier Temperature Dependence for the Polar GaN Surface

Origin of Surface Barrier Temperature Dependence for the Polar GaN Surface

Electromechanical coupling in free-standing AlGaN/GaN planar structures

Photoreflectance studiesof N‐ and Ga‐face AlGaN/GaN heterostructures confininga polarisation induced 2DEG

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