New structure GaP—GaAlP heterojunction cold cathode

A negative electron affinity (NEA) GaP-GaAlP cold cathode with a new junction structure is proposed and demonstrated by improved fabrication techniques. Emission efficiencies as high as 0.7-1.1 percent were obtained from these cathodes. The energy distribution of the emitted electrons from the cold cathode had a full width at half-maximum of about 0.3 eV. A resolution of about 500 TV lines was obtained with a sealed off 1-in vidicon tube having the cold cathode and an Sb2S3target. The electron beam temperature was about 650 K. At present, highly stable and long life NEA cold cathodes can only be obtained by improving the activation method. It is proposed that the NEA p-GaP surface can be stabilized by a Cs, Sb, and O2activation.