VARIABLE CAPACITOR Russian patent published in 1997 - IPC

FIELD: semiconductor instruments, in particular, devices which reactance is controlled by voltage. SUBSTANCE: device has semiconductor film with resistance contact which is located on semiconductor substrate of opposite conductivity with respect to film or on metal substrate. Working region of film 0 ≅ x ≅ x_max, z₁(x) ≅ z ≅ z₂(x) provides either non-uniform distribution of doping Ni(x, y), or non-uniform distribution of film depth D(x) or non-uniform distribution of doping and film depth. Film depth and doping distribution conform to condition of total depletion of working region of film with respect to charge carriers until barrier is broken under external bias voltage: , where Ui(x) is semiconductor film breaking voltage in section of x- y, y is coordinate which runs from film surface shared with substrate towards film depth; q is elementary charge; ε_s is dielectric permeability of semiconductor film; Uk is embedded potential. In addition resistance contact to film is made on free surface of its working region and is designed as strips which are connected to each other or as single strip. Function of capacitance on voltage C(U) in domain of external locking voltage U_min≅ U ≅ U_max is kept due to selection of function of working region film size F(x) = z₂(x) - z₁(x) in direction Z, or by selection of D(x) or Ni(x, y), where x, z are curvilinear orthogonal coordinates in plane of film surface shared with substrate (in particular, rectangular coordinates). Outside of working region doping distribution and film depth conform to condition of total depletion of film with respect to charge carriers under minimal external bias voltage at p-n junction (U = U_min): . EFFECT: increased functional capabilities. 4 cl, 5 dwg