RCA(美)公司研制了一种以光电子学为作用原理的电真空器件用的冷阴极。阴极的结构是这样的:一块砷化镓底片敷上一层10微米厚的P型砷化镓铝,然后再敷一层1微米厚的P~+型砷化镓。砷化镓铝层能很有效地产生光子,这些光子在通过上一层(砷化镓层)时激发出电子。由于砷化镓层中电子的逸出功很小,故电子能轻易地从阴极发射。 RCA (United States) company developed a photoelectron for the principle of electric vacuum devices cold cathode. The structure of the cathode is such that a piece of gallium arsenide film is coated with a 10-μm-thick P-type gallium aluminum arsenide and then a 1-μm-thick layer of P + -type gallium arsenide. The gallium aluminum arsenide layer produces photons very efficiently, and these photons excite electrons as they pass through the upper layer (the gallium arsenide layer). Since electrons in the gallium arsenide layer have a small work function, electrons can easily be emitted from the cathode.