Technology: AsGa, CMOS, bipolar

[semiconductor]

Can someone give me some basic information on these techs and some comparisons?

Thank you in advance.
Semi

 

[fede76pc]

Hi,
first of all I do not understand well your question in particular if you want to know if MOS or bipolar transistor can be realized in Gallium Arsenide (GaAs) technology.
However, GaAS is a compound III-V semiconductor with direct energy gap, high electron mobility,
low hole mobility, low intrinsic carrier concentration at ambient temperature. This makes it suitable for high speed devices and optoelectronics application (allowing heterojunction with its ternary or quaternary alloys). However, it as not a native oxide, so MOS structure could not be realized, but other kind of FET transistor are possible (MESFET, HEMT, PHEMT).

CMOS (Complementary MOS) is a technology for design integrated circuits (mainly digital but also analog ones) using both types of MOS transistors (nMOS and pMOS) working in conjunction.
In particular, considering a CMOS inverter, we have a pMOS and an nMOS transistor that never work together preventing any conducting path between bias voltage (Vdd) and ground. Thus no static power is dissipated and this is why technology scaling was possible.
As stated before CMOS is not possible over GaAs wafer due to the lack of an oxide. Moreover even if we deposit it chemically (using CVD for example), this oxide would have poor features. Moreover since holes have low mobility in GaAs, pMOS transistor would have very poor characteristics and this is also why CMOS is not possible over GaAs.

Bipolar could referred even to devices (Bipolar junction transistor , BJT) or any kind of technology adopting BJTs (eg TTL or ECL logic for digital circuits). Since BJT can be realized over GaAs (in particular the so-called Heterojucntion Bipolar Transistor or HBT) this kind of technologies can be made adopting a Gallium Arsenide wafer.

Best Regards,
Federico