Silicon as a material for resistors

Resistors may be formed from silicon both from the bulk material and by forming on the surface of the silicon diffused regions which are isolated from the bulk by a p¿n junction. This isolation is incomplete owing to leakage current and capacitance in the junction and to field-effect transistor action. Noise in silicon resistors should not be much larger than the Johnson noise except where noise is introduced at the contacts. Contacts having linear current/voltage characteristics may be made to silicon either by the formation of a highly doped layer of the same type or by the formation of a region of high minority-carrier recombination at the contact. The chemically reduced nickel contact is of the latter type. Experimental results are presented to show that it may prove adequate as a contact material for resistors under suitable conditions. A method for making such resistors is described.