The dependence of the differential negative resistance of a unijunction transistor (UJT) on external behavior is used to develop a new family of microelectronic transistors for measuring temperature, magnetic field, light radiation and pressure. The magnetic sensitivity of UJT in the presence of an externally applied magnetic field depends on this current magnetic effect. To our knowledge, there are no published results regarding the magnetic sensitivity of structures with p+ diffusion rings and surface recombination center regions.
Kim Sang Hyok, a section heat at the Institute of Semiconductor, proposed a unijunction transistor (UJT) of a new structure with enhanced galvanomagnetic effects by using a p+ diffusion ring and improved magnetic sensitivity by forming a recombination region on the surface with an emitter.
He fabricated the device on an n-type <111> orientation silicon mono-crystalline wafer with resistivity of 200Ω·cm and thickness of 250㎛ by using the standard CMOS technology.
The experimental results show that it had the highest magnetic sensitivity of 80V/T when the ratio of Emitter-Base 1 distance to diffusion length is about 1:0 and the width of the Base layer limited by the p+ diffusion loop is twice the Emitter width.
You can find more information in his paper “A New Structure of High-Sensitivity Magnetically Unijunction Transistor” in “Proceedings of KUTIC-2025”.