Memristors combine switching, memory, and rectification functions in two-terminal nanoelectronic devices. The theory says that their current-voltage (I-V) characteristics cross over at the zero crossing point (I = V = 0), and the results reported hitherto conform to this theorem. Here, we extend the family of memristive devices, adding memory diodes (memdiodes) comprising SrTiO3 pn junctions that display unique combination of rectification, hysteresis, and nonzero crossing. Reverse bias polarization gives rise to a nonzero open circuit voltage that persists after the junction is disconnected from the external circuit. This opens up an opportunity for a new type of nonvolatile memories.

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This article discusses the results obtained from an extensive comparison set up between nine different European laboratories using different two-dimensional ͑2D͒ dopant profiling techniques ͑SCM, SSRM, KPFM, SEM, and electron holography͒. This study was done within the framework of a European project ͑HERCULAS͒, which is focused on the improvement of 2D-profiling tools. Different structures ͑staircase calibration samples, bipolar transistor, junctions͒ were used. By comparing the results for the different techniques, more insight is achieved into their strong and weak points and progress is made for each of these techniques concerning sample preparation, dynamic range, junction delineation, modeling, and quantification. Similar results were achieved for similar techniques. However, when comparing the results achieved with different techniques differences are noted.

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We report on a method to quantitatively measure the local energy distribution of surface states density within the band gap of semiconductors using Kelvin probe force microscopy. The method is based on scanning a cross-sectional pn junction; as the tip scans the junction, the surface states position relative to the Fermi level changes, thereby changing the surface potential. The energy distribution is then obtained by fitting the measured surface potential. The method is applied to an oxidized Si (110) surface where a quantitative states distribution across most of the bandgap is obtained.