I want to know the answer to the following question:
What type of diode was used to help discover near-infrared light emission?
All the background I'm provided with is that "In September 1961, while working at Texas Instruments in Dallas, Texas, James R. Biard and Gary Pittman discovered near-infrared (900 nm) light emission from a tunnel diode they had constructed on a GaAs substrate.". Is that enough to answer the question?