The tunnel injection transit time (TUNNETT) diodes with p(+)p(+)n(+)n(-)n(+) structure were fabricated by liquid phase epitaxy (LPE). About 100 Angstrom tunnel junction (p(+)n(+)) was successfully prepared by the double impurity diffusion of Ge and S during LPE growth. Continuous wave (CW) oscillation was realized at 51.520 GHz in the V-band cavity with the phase noise of -60 dBc/Hz at 1 kHz bandwidth. (C) 2004 Elsevier Ltd. All rights reserved.