SiGe transferred electron device and oscillator using same

Abstract

This invention is a three layer Si.sub.x Ge.sub.1-x structure formed on a silicon substrate in which a thin, lightly doped Si.sub.x Ge.sub.1-x layer is formed between two heavily doped Si.sub.x Ge.sub.1-x layers. The incorporation of at least 10% germanium in the silicon provides for intervalley scattering of carriers in the conduction band of the Si.sub.x Ge.sub.1-x layers. This intervalley scattering leads to the negative differential conductance necessary for transferred electron device (TED) operation. Additionally, the lightly doped Si.sub.x Ge.sub.1-x layer is made very thin, on the order of 2,000 to 7,000 Angstroms, and the current flow through the this layer is vertical so that a high electric field can be placed across the lightly doped layer without applying a high voltage across the lightly doped layer. The lightly doped layer can be made thin even though it is interposed between two heavily doped layers because the growth of the in-situ doped Si.sub.x Ge.sub.1-x layers is carried out at a temperature of less than approximately 600.degree. C. When the growth of the Si.sub.x Ge.sub.1-x layers is done in this temperature range, then there is no outdiffusion of the dopants from the heavily doped layers into the lightly doped layers and abrupt doping profiles are maintained even over relatively short distances in the layers. The TED can be connected to an RLC network formed on the silicon substrate to form an integrated oscillator circuit.

Dependencies are inferred from the claim text.