We report simultaneous transport and scanning Microwave Impedance Microscopy to examine the correlation between transport quantization and filling of the bulk Landau levels in the quantum Hall regime in gated graphene devices. Surprisingly, comparison of these measurements reveals that quantized transport typically occurs below complete filling of bulk Landau levels, when the bulk is still conductive. This result points to a revised understanding of transport quantization when carriers are accumulated by gating. We discuss the implications on transport study of the quantum Hall effect in graphene and related topological states in other two dimensional electron systems.

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Nowvolatile memory processes, in particular the EEPROM process, is one the hardest process to be developed. Compared to a CMOS process, the EEPROM process has extra requirements which are high voltage transistors (>16V), EEPROM cells, ONO layers, the buried N+ layer, thin tunnel oxide and stacked poly gates. EEPROM devices are judged on the programming speed, which relates to program high (erase) and program low (write) operations. It is essential that the program high and program low speed of the EEPROM cell is within lms with a programming voltage of not more than 16V.Two experiments were setup to improve the programming speed. The fmt experiment was to increase the high voltage NMOS drain junction breakdown voltage with the source floating (AVNMOS BWSF), and the second experiment was to scale down the ONO layer.The characterization work to increase the programming speed of the memory cells of a 16k FLOTOX EEPROM device has been carried out. P-field implant dose is optimized to have both the HVNMOS BWSF and the p field threshold above 16V for fast programming. A program high threshold voltage ( V , ) of 4.5V and a program low threshold voltage (VtL) of -0.94V are achieved.