The discovery of Coulomb blockade effects revised the noise models of several mesoscopic and macroscopic devices. To check the proper noise model for p-n junction, the bandwidth is measured over which the external field amplitude fluctuation of a semiconductor laser is reduced to below the standard quantum limit. For macroscopic p-i-n junction, the noise of the injected electron stream is sub-Poissonian only at frequencies below that given by the inverse of the thermionic emission line. This shows that optical squeezing bandwidth of semiconductor lasers and LEDs will be limited by rate of thermionic injection at high temperature and small current.