I. Fluctuations in Luminescent Junctions Ii. Measurements on Semiconductor Pn Junctions Ui. Photomultiplier Tube Noise Iv. Calculation of Fluctuations in Optical Absorption v. Current Noise in Cadmium Telluride

Optical emission fluctuations from a GaAs and a Ga(AsP) luminescent diode, as well as from a GaAs junction laser, have been measured. Correlation is observed between optical emission noide and forward current noise of the diode, suggesting that carrier transitions responsible for both effects are the same. Diodes in which considerable carrier recombination occurs in the space charge region exhibit characteristic time constants in both the optical noise and forward current noise. More heavily doped junctions in which tunneling dominates yield only 1/f noise spectra. Only photon noise is observed from diodes in which the junction current is by carrier diffusion. It is possible to measure non-destructively all important p-n junction parameters of luminescent diodes by judicious choice of experimental techniques. Thus, the junction area, width, internal potential, saturation current, and impurity content can be determined. This facility results from the application of standard electrical measurements coupled with optical properties of such diodes. Additional work carried out on optical absorption fluctuations in germanium shows that previous unsuccessful experimental attempts to detect the effect are consistent with the analytical prediction of the magnitude. Finally, preliminary experimental noise measurements in single-crystal CdTe suggest that the dominant effect is shot noise associated with internal inhomogeneities. NT RESEARCH INSTITUTE