The Double-Heterostructure Concept: How It Got Started

Abstract

The double-heterostructure (DH) concept for lasers and light-emitting diodes (LEDs) grew out of the prelaser context of increasing the speed of the early bipolar junction transistors. The 1954 idea was to change the energy gap itself, with a graded-gap base, or a wide-gap emitter. This led to the 1957 more general concept of quasi-electric fields and potentials in structures with a position-dependent energy gap. This paper gives a personal chronological account of the evolution of these concepts toward the 1963 proposal of the DH laser, including some blind alleys and blunders along the way.