New resonant tunneling bipolar transistor (RTBT) with multiple negative differential resistance characteristics operating at room temperature with large current gain

A novel resonant tunneling bipolar transistor with two peaks in the output as well as the transfer characteristics is reported. The multiple peaks are obtained by sequentially quenching resonant tunneling through the ground states of a series of double-barrier quantum wells, placed in the emitter of a Ga/sub 0.47/In/sub 0.53/As n-p-n bipolar transistor, thus obtaining nearly equal peak currents and peak-to-valley ratios. The transistor exhibits current gain of about 70 at room temperature and 200 at 77 K. Peak-to-valley ratios at room temperature and at 77 K are as high as 4:1 and 20:1, respectively. The transistor has been used to design frequency-multiplier and four-bit-parity-generator circuits. A one-transistor circuit multiplies the frequencies of sawtooth and sinewave input signals by factors of three and five, respectively. The four-bit-party generator requires only one transistor, as compared to 24 needed in conventional circuits.<>