The cathodoluminescence (CL) detection system combined with a transmission electron microscope (TEM) was built up and was applied to a study of the defects in GaAs, diamond and MgO crystals. The effects of accelerating voltage, specimen thickness and specimen temperature on the CL intensity and spectrum were studied for finding a proper experimental condition. The monochromatic CL images clearly revealed the luminescent dislocations in the type IIb diamond crystal and the luminescence is attributed to the Donor to Acceptor transition mechanism of impurity atoms such as nitrogen, boron and nickel. The deformed regions along the slip band in the MgO crystal showed a bright contrast in the monochromatic CL image with the wavelength of 450 nm, which is considered to be due to the luminescence center related to vacancy. The dislocation bundle in a Si-doped GaAs crystal gives rise to the decrease of the CL intensity, and a shift of the peak wavelength was observed in the CL spectrum from the dislocation bundle, which is due to the narrowing of the energy band gap by elastic strain field. The CL system is also used for detecting the Cherenkov radiation with a light collection mirror set beneath the specimen holder. The Cherenkov radiation was observed from the dielectric materials such as mica and quartz, which showed spectra having a characteristic shape (the λ-2-dependence), and disappeared at the accelerating voltage below the threshold one.
(Received April 24, 1990)
Keywords: cathodoluminescence, transmission electron microscope, semiconductor, GaAs, dislocation, Cherenkov radiation
* Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152, Japan.