From transistors to light emitters

The report at the 1962 IRE Solid-State Device Research Conference (July, Durham, NH) of the generation and long-range transmission (and detection) of a recombination-radiation signal from a simple Zn-diffused GaAs p-n junction, a startling report, began the race to construct a semiconductor laser. The visible-spectrum II-V alloy GaAs/sub 1-x/P/sub x/ was in the middle of this activity and was (fall of 1962), with GaAs, a first semiconductor laser, not to mention the first laser in a semiconductor alloy or crystal that could be "tuned" in energy gap (and wavelength) from direct gap to indirect gap. The ternary GaAs/sub 1-x/P/sub x/, the prototype of all present-day III-V alloys used in heterojunction and quantum-well devices, established uniquely the importance of a direct gap for a laser and inevitably for light emitting diodes (LEDs). The events leading to the GaAs/sub 1-x/P/sub x/ laser, as well as, in slightly different form, the first practical LED, are described. The significance of the work of 1962-1963 in launching the semiconductor laser is described, and the reasons why the semiconductor laser (an "ultimate lamp") is predominant over all other forms of lasers.