The effect of hole leakage and Auger recombination on the temperature sensitivity of GaInAsSb/GaSb mid-infrared lasers

Lasers emitting in the 2-3μm mid-infrared spectral window have numerous applications. Non-radiative processes such as Auger recombination and carrier leakage cause increased threshold current density (Jth) with increasing temperature and as a result, limit their maximum operating temperature for lasers operating in this wavelength range [1]. In type-I interband devices, the band gap determines the wavelength, hence investigating the effects of band gap shift on the device properties provides a means of optimisation. In this work, temperature and hydrostatic pressure have been used independently to tune the bandgap of GaInAsSb type-I edge emitting lasers. The dependence of Jth, Auger current (JAuger) and radiative current (Jrad) on the band gap of these devices is presented (Fig. 1a). Results show that by applying pressure, the T0 of the 2.6μm device increases from 37±5K up to ~53±5K (Fig.1b) when operating at 2.3μm under pressure. This value is similar to the as-grown 2.3μm for which T0 =59±5K (Fig. 1a). However, Jth is ~25% higher compared to an as-grown 2.3μm device. This difference is due to the fact that the as-grown 2.3μm device maintains larger band offsets than the pressure-tuned 2.3μm device. Hence, the reduced Jth of the as-grown device may be associated with a lower carrier leakage current. Whilst the larger band offset helps reduce Jth it makes little difference to its temperature sensitivity in these type-I GaInAsSb/GaSb devices. This indicates that further optimisation of the band offset would bring little benefit in terms of T0 and that reducing the Auger process would be of much larger benefit. We also show that non-pinning of the carrier density above threshold and intervalence band absorption cause the external differential efficiency of these devices to decrease with increasing temperature.

The dependence of Jth, Auger current (JAuger) and radiative current (Jrad) on the band gap of these devices is presented (Fig. 1a). Results show that by applying pressure, the T0 of the 2.6μm device increases from 37±5K up to ~53±5K (Fig.1b) when operating at 2.3μm under pressure. This value is similar to the as-grown 2.3μm for which T0 =59±5K (Fig. 1a). However, Jth is ~25% higher compared to an as-grown 2.3μm device.