The threshold current density, Jth, and its radiative component, Jrad, in 1.55 μm InAs/InP (100) quantum dot lasers are measured as a function of temperature and hydrostatic pressure. We find that Jrad is relatively temperature insensitive. However, Jth increases significantly with temperature leading to a characteristic temperature T0=72 K over the range 220–290 K. Nonradiative recombination accounts for up to 94% of Jth at T=293 K. Jth decreases with increasing pressure by 35% over 8 kbar causing an increase in T0 from 72 to 88 K. The results indicate that nonradiative Auger recombination determines temperature behavior of these devices and T0 value.
Semiconductor lasers with quantum dot (QD) based active regions have generated a huge amount of interest for applications including communications networks due to their anticipated superior physical properties due to three dimensional carrier confinement. For example, the threshold current of ideal quantum dots is predicted to be temperature insensitive [1]. We have investigated the operating characteristics of 1.55 µm InAs/InP (100) quantum dot lasers focusing on their carrier recombination characteristics using a combination of low temperature and high pressure measurements. By measuring the intrinsic spontaneous emission from a window fabricated in the n-contact of the devices we have measured the radiative component of the threshold current density, J rad . We find that J rad is itself relatively temperature insensitive (Fig. 1). However, the total threshold current density, J th , increases significantly with temperature leading to a characteristic temperature T 0~7 2K around 220K-290K. From this data it is clear that the devices are dominated by a non -radiative recombination process which accounts for up to 94% of the threshold current at room temperature (Fig. 1).
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