n-Si/SiO2/Si heterostructure barrier varactor diode design

Symmetric C-V and antisymmetric I-V characteristics are essential for a heterostructure barrier varactor (HBV) to generate odd harmonics in a frequency multiplier. Practically high multiplier efficiency is obtained when the shape of the C-V characteristic is sharp near zero bias and the conduction current is low. Here we present the design of an n-type Si/SiO2/Si-based HBV and its state-of-the-art device performance. Self-consistent solutions of the Schrodinger and Poisson equations show a drastic decrease of the conduction current due to the large electron effective mass and the SiO2 barrier height. The shape of the C-V curve can be easily tuned by modifying the thickness of the SiO2 layer. By the techniques compatible with the conventional Si technology, a Si/SiO2/Si varactor junction (having a SiO2 layer of 20 nm) has been processed and the device characteristics are very promising. (C) 2000 American Institute of Physics. [S0003-6951(00)01827-1].