Active and buffer layers of GaN HEMT: ECV profiling and 2DEG calculation

ABSTRACT

Gallium nitride transistors with high electron mobility (HEMT) have been studied by means of electrochemical capacitance–voltage (ECV) technique. The capacitance–voltage characteristics at various frequencies were measured; the free charge carrier depth distributions as well as the intensity of quantum well filling by charge carriers were obtained. The features of 2D electron gas (2DEG) appearance in GaN HEMT, related to spontaneous and piezoelectric polarisation, as well as factors affecting the density of free charge carriers in channel and the performance of GaN HEMTs were described in detail. The efficiency of ECV technique for quality control of both active and buffer layers of GaN HEMT heterostructures is shown. The calculation of 2DEG density for various technological parameters of the interface, such as mutual orientation of AlGaN/GaN layers and composition of Al_xGa_1-xN, is carried out taking into account piezoelectric effects.

KEYWORDS:

• Electrochemical capacitance–voltage profiling
• heterostructure
• HEMT
• quantum well
• gallium nitride
• simulation
• piezoelectric polarisation

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No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

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Notes on contributors

George Yakovlev

George Yakovlev is Ph.D., assistant at department of micro- and nanoelectronics of St. Petersburg State Electrotechnical University (LETI), specialist in the field of capacitive spectroscopy of semiconductors

Vasily Zubkov

Vasily Zubkov is Doctor of Sc., professor at department of micro- and nanoelectronics of St. Petersburg State Electrotechnical University (LETI), recognized specialist in the field of admittance spectroscopy and simulation of quantum-sized semiconductor heterostructures

Anna Solomnikova

Anna Solomnikova is Engineer at Department of micro- and nanoelectronics of St. Petersburg State Electrotechnical University (LETI), specialist in the field of atomic-force microscopy and admittance spectroscopy