Double electron drift device as a magnetic field sensor
A new magnetic field sensor based on electron transport in the depletion region of reverse-biased silicon pin diodes is presented. Its field sensitivity is derived from transport equations with magnetic fields. The new sensor consists of a pin diode across the silicon wafer, an injection line within the anode, and opposite to this line a gap, which splits the cathode into two halves. The fabrication of the pin diodes is compatible with CMOS technology. The fabrication required layer processing on both wafer sides, transfer of alignment markers from one side to the other. Magnetic measurements revealed the following main results: the magnetic field sensitivity was 1.6 T?1, i.e. 23 times larger than that of Hall probes. All measured field sensitivities were in accordance with theoretical predictions. At high injection currents a reduction of the field sensitivity is observed which is caused by beam broadening due to space charge effects. Due to the alignment accuracy of less than 1 ?m magnetic offsets of up to 0.05 T were observed.
electron drift space charge magnetic sensor silicon device electron diffusion