Bipolar transistor memory

Bipolar transistor memory, with a typical cycle time 300 nsec, is still faster but more expensive. It is contructed from complex integrated circuits. 

SiC bipolar transistors have been fabricated and measured. Improved performance is to be expected in heterojunction devices with a wider bandgap emitter. A feasibility study is underway to make a non-volatile random access memory in SiC. 

MOSFETs. The metal-oxide-semiconductor field effect transistor (MOSFET or MOS transistor) (8) is the most important device for very-large-scale integrated circuits, and it is used extensively in memories and microprocessors. MOSFETs consume little power and can be scaled down readily. The process technology for MOSFETs is typically less complex than that for bipolar devices. Figure 12 shows a three-dimensional view of an n-channel MOS (NMOS) transistor and a schematic cross section. The device can be viewed as two p-n junctions separated by a MOS capacitor that consists of a p-type semiconductor with an oxide film and a metal film on top of the oxide. 

This Datareview describes recent progress in bipolar junction transistors, thyristors and random access memories made in SiC. The first two device types have been made in both cubic and hexagonal SiC polytypes. The first random access memory made in hexagonal SiC will be described. 

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