Three-dimensional magnetic-field sensors

Devices sensitive to all three components of a magnetic-field vector are presented. The sensitivity to two field components in the plane of the chip is achieved by merging two one-dimensional vertical magnetotransistors positioned at a 90° angle to each other. An additional surface-collector pair makes this device also sensitive to the last field component, which is perpendicular to the plane of the chip. The sensitivity of the 3-D sensor is represented by a nondiagonal sensitivity-matrix. The smallest achieved sensitive volume is (6×10×16) μm³, which is limited by the design tolerances. The elements of the sensitivity matrix of the device are discussed along with the parameters that influence them. The influence of additional collector pairs on the sensitivity is also discussed. Several 3-D sensitive structures are presented, including magnetotransistor and resistive structures     

Two-dimensional imaging of cleaved Si p-n junctions with 30-nmresolution using a UHV scanning tunneling microscope

The first two-dimensional scanning tunneling microscope (STM) measurements on cleaved shallow silicon p-n junctions are presented. The current imaging technique provides contrast between p- and n-type regions on biased junctions. The two-dimensional part of the junction is imaged and localized to within 30 nm. Both the cleaving of the junction and the STM measurements are performed in ultrahigh vacuum (UHV)