Long wavelength bulk absorption cutoffs in GaAs light-emitting diodes exhibiting vacuum and gamma-irradiation emission wavelength tunability

Absorption edge measurements indicate hardly any change in long wavelength detection cutoff of GaAs shallow-junction surface-emitting LED´s as a result of pressure effects. This supports the concept that vacuum-induced significant emission wavelength tuning of these devices is a result of surface effects rather than changes in Eg. Also, possible slight decrease of long wavelength cutoff in these devices via gamma irradiaition, while emission wavelength is shifted significantly to longer wavelengths, proves that γ-irradiation spectral tuning of them does not derive from bulk bandgap changes and supports the concept that emission wavelength increase in these shallow-junction devices is a result of effects of γ-irradiation on surface emission rather than on Egin the bulk.