METHOD OF CONTROL OVER VOLTAGE IN OPEN STATE OF THYRISTORS AND DIODES Russian patent published in 1998 - IPC

FIELD: power semiconductor equipment. SUBSTANCE: method of control over voltage in open state of thyristors and diodes consists in irradiation of lot of rectifying elements by flow of fast electrons, γ - quanta or protons. Voltage V is determined in advance across each i-th rectifying element with specified i_s, and τ, and value of radiation dose Φ_1i is found from relations U₃ - ΔU₃ ≤ U_ki≤ U₃+ΔU₃ ;; ; , where U_s is voltage of rectifying element with i_s; U_ki - is actual value of V of i-th rectifying element after its irradiation with i_s; ΔU is permissible value of deviation of U_ki from U_s; ξ is maximum value of coefficient for thyristors or diodes during irradiation that is determined in other rectifying elements of same type beforehand; K is Boltzmann's constant; T is temperature of rectifying element during measurement of V; W is width of effective base region; L_0i and τ_0i are diffusion length and life time of minority carriers in effective base region of i-th rectifying element before irradiation; K_τ is maximum value of coefficient of degradation of life time of minority carriers determined in advance in other rectifying elements; D^* is ambipolar coefficient of diffusion. Across rectifying elements not satisfying condition (I) voltage V is controlled with i_s and τ in each i-th rectifying element after irradiation and repeat irradiation is conducted which value of dose per each i-th rectifying element should meet conditions: (I); ; ; ; ; ; . EFFECT: improved reliability of method. 2 tbl