Tunneling-determined threshold current in Pb1−xSnxTe diode lasers

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Abstract
The current transport mechanism in n+-n-p+ homostructure diode lasers of Pb1−xSnxTe prepared by liquid-phase epitaxy was studied using measurements of the I-V characteristics as a function of temperature. It is found that the lasing threshold is dominated by excess tunneling current and not by diffusion current as previously assumed. To the best of our knowledge this is the first attempt to study the diffusion component of the injected current which determines the population inversion, and hence the threshold current, by analyzing the I-V characteristics. The results of this work raise some doubt about the validity of the existing theoretical calculations of the threshold current in lead-salt diode lasers.