THEORETICAL ANALYSIS OF HETEROJUNCTION DOUBLE BARRIER DIODES FOR LOGIC APPLICATIONS

THE USE OF LOGIC CIRCUITS EMPLOYING HETEROJUNCTION DOUBLE BARRIER DIODES WITH NEGATIVE DIFFERENTIAL RESISTANCE REGIONS WILL BE EXAMINED THEORETICALLY. SWITCHING TIME LIMITATIONS WILL BE ESTIMATED BASED ON CIRCUIT CONSIDERATIONS AND THE DEVICE ARCHITECTURE. FUNDAMENTAL LIMITATIONS ARISING FROM RIGOROUS UNITARITY BOUNDS AND DISPERSION EFFECTS INVOLVING QUANTUM MECHANICAL RESONANT TUNNELING TIME DELAY WILL BE INCLUDED. THE FUNDAMENTAL LIMIT CONSIDERATIONS ARE SUFFICENTLY GENERAL TO APPLY TO BARRIERS WITH ARBITRARY SHAPE. PRELIMINARY THEORETICAL ESTIMATES INDICATE THAT PICOSECOND OR SUBPICOSECOND SWITCHING TIMES MIGHT BE ACHIEVABLE WITH APPROPRIATELY DESIGNED AL(X)GA(1-X)AS/GAAS DEVICES. THESE SWITCHING TIMES ARE SO SHORT THAT IT BECOMES IMPORTANT TO EXAMINE ALL EFFECTS WHICH COULD LIMIT PERFORMANCE.