MBEによるGaAs-AlGaAsヘテロ構造とその素子への応用

抄録

Quasi-two-dimensional electron gas accumulating at the heterojunction interface in selectively doped GaAs/N-Al_xG_al-xAs (x_??_O.3) grown byMBE showed extremely high mobility at low temperatures. The maximum mobilities attained at 77K and 4.2K were 117, 000cm²/Vs and 244, 000cm²/Vs, respectively, with sheet electron concentration of about 4.9x1011cm-2. Eventhe value at 77 K is almost 25 times as high as that of a conventional GaAs MESFET. High electron mobility transistors (HEMT's) were fabricated from the heterostructure material, which showed excellent high-speed performance at low temperatures.
An enhancement-mode HEMT with a short gate (gate length L_G=2μm, gate width W_G=300μm) exhibited transconductance as high as 193ms/mm of the gate widthat 300 K and 409ms/mm at 77 K; the latter is the highest transconductance ever reported for field effect transistors. Consequently, this device has great potential for application as a post-silicon device in high-speed, low-power dissipation integrated circuits.