Piezoelectric actuation of (GaN/)AlGaN/GaN heterostructures

A detailed analysis of the piezoelectric response of (GaN/)AlGaN/GaN heterostructures is reported. The electromechanical properties of two types of heterostructures with an Al content of 31% are compared. Only a single two-dimensional electron gas (2DEG) is formed for samples with thin GaN cap layers, while both a 2DEG and a two-dimensional hole gas coexist in the case of thick GaN caps. The lower GaN layer represents the mechanically supporting layer, while the AlGaN film, and in some cases an additional GaN cap layer, serves as the piezoelectrically active layers for actuation. The 2DEG (at the lower AlGaN/GaN interface) provides the conducting channel which was used as back electrode for the applied external voltage. Electroreflectance spectroscopy is applied in order to determine the electric field distribution across the whole structure as a function of the applied voltage. It is found that only a part of the modulation voltage drops across the active region. Piezoelectric force microscopy yields the...

[1]  Lester F. Eastman,et al.  Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures , 1999 .

[2]  Oliver Ambacher,et al.  Growth and applications of Group III-nitrides , 1998 .

[3]  Uwe Rossow,et al.  Dielectric function and critical points of the band structure for AlGaN alloys , 2005 .

[4]  Amit K. Gupta,et al.  Single virus particle mass detection using microresonators with nanoscale thickness , 2004 .

[5]  Jacek A. Majewski,et al.  Pyroelectric properties of Al(In)GaN/GaN hetero- and quantum well structures , 2002 .

[6]  O. Ambacher,et al.  Piezoresponse force microscopy for polarity imaging of GaN , 2002 .

[7]  B. Jogai,et al.  Influence of surface states on the two-dimensional electron gas in AlGaN/GaN heterojunction field-effect transistors , 2003 .

[8]  Harold G. Craighead,et al.  Virus detection using nanoelectromechanical devices , 2004 .

[9]  H. Craighead,et al.  Attogram detection using nanoelectromechanical oscillators , 2004 .

[10]  P. Muralt,et al.  Thickness dependence of the properties of highly c-axis textured AlN thin films , 2004 .

[11]  Chr Edelmann,et al.  Miniaturized vacuum gauges , 2004 .

[12]  M. Eickhoff,et al.  Determination of the polarization discontinuity at the AlGaN∕GaN interface by electroreflectance spectroscopy , 2005 .

[13]  Y. Morilla,et al.  Comparative study of c-axis AlN films sputtered on metallic surfaces , 2005 .

[14]  O. Ambacher,et al.  Pulsed mode operation of strained microelectromechanical resonators in air , 2006 .

[15]  Current versus voltage characteristics of GaN∕AlGaN∕GaN double heterostructures with varying AlGaN thickness and composition under hydrostatic pressure , 2008 .

[16]  O. Ambacher,et al.  Electric field distribution in GaN∕AlGaN∕GaN heterostructures with two-dimensional electron and hole gas , 2008 .

[17]  A. Kingon,et al.  Measurement of the effective piezoelectric constant of nitride thin films and heterostructures using scanning force microscopy , 2001 .

[18]  Martin Eickhoff,et al.  Piezoresistivity of AlxGa1−xN layers and AlxGa1−xN/GaN heterostructures , 2001 .

[19]  Electromechanical coupling in free-standing AlGaN/GaN planar structures , 2003, cond-mat/0306323.

[20]  S. Muensit,et al.  Extensional piezoelectric coefficients of gallium nitride and aluminum nitride , 1999 .

[21]  R. T. Webster,et al.  Bias induced strain in AlGaN∕GaN heterojunction field effect transistors and its implications , 2006 .

[22]  Charles Surya,et al.  Piezoelectric coefficient of aluminum nitride and gallium nitride , 2000 .

[23]  S. S. Park,et al.  Effects of hydrostatic and uniaxial stress on the Schottky barrier heights of Ga-polarity and N-polarity n-GaN , 2004 .

[24]  K. Korona,et al.  Electroreflectance and photoreflectance spectra of tricolor III‐nitride detector structures , 2007 .

[25]  João Pedro Conde,et al.  Electrostatically actuated resonance of amorphous silicon microresonators in water , 2006 .

[26]  Peter Veit,et al.  Metalorganic chemical vapor phase epitaxy of gallium-nitride on silicon , 2003 .

[27]  Hadis Morkoç,et al.  Effect of hydrostatic pressure on the dc characteristics of AlGaN∕GaN heterojunction field effect transistors , 2006 .

[28]  M. R. Freeman,et al.  Multifunctional Nanomechanical Systems via Tunably Coupled Piezoelectric Actuation , 2007, Science.

[29]  I. L. Guy,et al.  The piezoelectric coefficient of gallium nitride thin films , 1998 .

[30]  Oliver Ambacher,et al.  Piezoelectric properties of polycrystalline AlN thin films for MEMS application , 2006 .

[31]  D. DeVoe,et al.  Piezoelectric bfmorph transducers based on single crystal AL/sub 0.3/Ga/sub 0.7/AS films , 2005, 18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005..

[32]  Toshio Kamiya,et al.  Calculation of Crystal Structures, Dielectric Constants and Piezoelectric Properties of Wurtzite-Type Crystals Using Ab-Initio Periodic Hartree-Fock Method , 1996 .

[33]  Amir Dabiran,et al.  Effects of hydrostatic and uniaxial stress on the conductivity of p-type GaN epitaxial layer , 2002 .

[34]  O. Ambacher,et al.  Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications , 2007 .

[35]  Don L. DeVoe,et al.  Piezoelectric thin film micromechanical beam resonators , 2001 .

[36]  H. Craighead,et al.  Enumeration of DNA molecules bound to a nanomechanical oscillator. , 2005, Nano letters.

[37]  Michael J. Uren,et al.  Structural and electrical characterization of AuTiAlTi/AlGaN/GaN ohmic contacts , 2002 .

[38]  E. Kohn,et al.  Piezoelectric GaN sensor structures , 2006, IEEE Electron Device Letters.