Heterojunction Bipolar Transistors HBTs

3 High Electron Mobility Transistors (Modulation Doped Field Effect Transistors [HEMTs (MODFETs)] 

The major applications of lasers are CD players, optical storage devices including CD-ROM (optical read-only memory), WORM (write once, read many times) and true optical disks (unlimited read and write). The amount of information that can be packed on a disk presently is limited to the size of the spot generated by the laser. The shorter the wavelength, the smaller the spot. Other applications include laser printers, spectroscopy, and communications. Lasers operating at 1.3 micrometers and 1.55 micrometers are used for low loss quartz fiber optic communications. AlGaAs is used for 

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Some of tliese problems are avoided in heterojunction bipolar transistors (HBTs) [jU, 38], tlie majority of which are based on III-V compounds such as GaAs/AlGaAs. In an HBT, tlie gap of tlie emitter is larger tlian tliat of tlie base. The conduction and valence band offsets tliat result from tlie matching up of tlie two different materials at tlie heterojunction prevent or reduce tlie injection of tlie base majority carriers into tlie emitter. This peniiits tlie use of... 

Heterogenous immunoassays, 14 151-152 Heteroglycans, 4 697, 702 23 64 Hetero-interface, 24 71 Heterojunction, 23 34 Heterojunction bipolar transistors (HBTs), 22 166-169... 

Field-effect transistors (FETs) Heterojunction bipolar transistors (HBTs) High electron mobility transistors (HEMTs) Metal oxide semiconductor FETs (MOSFETs) Single-electron transistors (SETs) Single-heterojunction HBTs (SH-HBTs) Thin-film transistors (TFTs) hydrogenated amorphous silicon in, 22 135... 

There has been active interest in new transistor-like devices compatible with superconductivity for a number of years (39). Part of the interest derived from difficulties in using the two-terminal Josephson device in digital circuitry. With the discovery of superconductors with transition temperatures above 77 K, the device needs and opportunities need to be reassessed. MOSFFFs, GaAs HEMT s, and heterojunction bipolar transistors (HBT s) work well at 77K, so... 

Figure 4-30. Schematic of heterojunction bipolar transistor (HBT) device.

For a heterojunction bipolar transistor (HBT), a theoretical study was also reported for SiC/Si/diamond (emitter/base/collector, respectively) (7), and the HBT FOM is 22.21 times larger than for an AlGaAs/GaAs/GaAs HBT. Here, the HBT FOM is defined as the product of operating frequency and output power of the HBT with 3 dB gain. This is also possible... 

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