Carrier transport in stripe-geometry Ga1−xAlxAs double heterostructure diode lasers and broad area heterojunctions

Publisher Website
Google Scholar
Abstract
The current‐voltage characteristics of stripe‐geometry double heterostructure diode lasers and broad area heterojunctions of Ga1−xAlxAs prepared by liquid‐phase epitaxy have been extensively studied as a function of temperature and diode area to perimeter ratio. For stripe‐geometry lasers, current‐voltage measurements were made up to the lasing threshold (∼104 A/cm2). The carrier transport mechanisms in different ranges of current densities were identified and interpreted on the basis of existing models for p‐n junctions. It is found that 2‐kT current in combination with a tunneling current of the form I α exp(T/T0) exp(AV) where T0 and A are constants essentially independent of temperature, are the major contributions to the diode current at low forward bias. The 2‐kT current is most probably due to surface recombination occurring at the junction perimeter and the tunneling current is most probably related to defects generated in the diode depletion region during epitaxial growth and/or sample processing. At medium forward bias, pure 1‐kT current limited by the rate at which electrons can diffuse in the narrow gap p‐type semiconductor is dominant. In the laser devices 2‐kT current consistent with high injection conditions, is found at current densities near threshold. To the best of our knowledge, this is the first time high injection behavior has been recognized and demonstrated in diode laser devices.