By self-consistently solving Schrodinger and Poisson equations, an extremely high two-dimensional electron-gas (2DEG) sheet density of 1.01 x 10(14) cm(-2) is calculated in a novel InN-based InxGa1-xN/InN heterostructure field-effect transistor with an In content of x = 0.1 and a doping level of N-d = 1 x 10(19) cm(-3) in the InxGa1-xN barrier layer. It is increased by almost one order of magnitude as compared to similar to1 x 10(13) cm(-2) obtained in a conventional GaN-based Al0.2Ga0.8N/GaN heterostructure. With increasing In content of the InxGa1-xN barrier from x = 0.05 to 0.15, the 2DEG sheet density decreases from 1.14 x 10(14) cm(-2) to 0.91 x 10(14) cm(-2) due to the decreased of polarization charges and the reduced conduction band offset. And the 2DEG density increases slightly with increasing doping level of the InxGa1-xN barrier. (C) 2004 Elsevier Ltd. All rights reserved.