p-Channel (Al,Ga)As/GaAs modulation-doped logic gates

The operation of logic gates composed of modulation-doped field-effect transistors based on two-dimensional hole-gas conduction is reported for the first time. Direct coupled inverters fabricated on an MBE grown Be-doped (Al,Ga)As/GaAs wafer having a sheet density of 1.5 × 10
¹²
cm
^-2
and a 77K mobility of 1800 cm
²
/V.s exhibit logic states of -0.25 and -0.98 V at 77K for a - 1-V bias. Propagation delays of 233.0 ps/gate are obtained at 77K in ring-oscillator circuits with a power dissipation of 0.31 mW/gate. Power-delay products as low as 9.1 fJ are also obtained.