Recombination processes in midinfrared InGaAsSb diode lasers emitting at 2.37μm

Abstract

The temperature dependence of the threshold current of InGaAsSb/ AlGaAsSb compressively strained lasers is investigated by analyzing the spontaneous emission from working laser devices through a window formed in the substrate metallization and by applying high pressures. It is found that nonradiative recombination accounts for 80% of the threshold current at room temperature and is responsible for the high temperature sensitivity. The authors suggest that Auger recombination involving hot holes is suppressed in these devices because the spin-orbit splitting energy is larger than the band gap, but other Auger processes persist and are responsible for the low T 0 values. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2243973͔ Diode lasers emitting in the midinfrared ͑MIR͒ are important for the development of highly sensitive gas detection systems. Many gases of interest have strong absorption lines in the 2 -5 m region, where the InGaAsSb material system is proving successful. 1,2 Threshold current densities as low as 58 A cm −2 per quantum well ͑QW͒ for devices emitting at 2.24 m and 66 A cm −2 per QW at a wavelength of 2.26 m have been achieved, 3,4 while continuous-wave maximum output powers of 500 mW near 2.3 m have been recorded. 5 Previously, investigations of the variation in spontaneous emission characteristics with temperature have successfully been used to examine and optimize the properties of nearinfrared semiconductor lasers for optical fiber communications. 6,7 The application of these techniques to midinfrared lasers will aid the development of these particular devices and further the overall understanding of this material system. In this letter, we investigate the carrier recombination processes occurring in 2.37 m InGaAsSb/ AlGaAsSb lasers, over a wide temperature range from 80 to 300 K and using high hydrostatic pressures up to 8 kbar. From these data we identify the dominant recombination paths constituting the threshold current of the devices and the extent to which each process influences their temperature dependence.The triple quantum well lasers under investigation were grown by solid-source molecular beam epitaxy on GaSb substrates. Two 35 nm Al 0.25 Ga 0.75 As 0.02 Sb 0.98 barriers separate the 10 nm thick, 1.4% compressively strained In 0.35 Ga 0.65 As 0.11 Sb 0.89 QWs, providing a type I band alignment at the QW/barrier interface. Standard photolithography techniques were used to fabricate lasers with a 100 m-wide metal contact stripe. The p and n contacts consist of Pt/ Au and a thick gold layer deposited, respectively. 8 Fabry-Pérot lasers were measured as-cleaved with a cavity length of 1 mm.In order to collect the spontaneous emission from the device, a 100 m diameter circular window was milled in the n contact, using a focused ion beam. This enables one to collect pure spontaneous emission which has been unaffected by gain or loss along the cavity. Further details of the technique can be found elsewhere. 6 The emitted spontaneous emission was collected using a chalcogenide ͑A...

Carrier dynamics and photoluminescence quenching mechanism of strained InGaSb/AlGaSb quantum wells

“…Some suggested that non-radiative Auger recombination is the most detrimental mechanism which limits the performance of the low band-gap longwavelength semiconductor lasers. [19][20][21][22] On the other hand, Shterengas et al 23,24 and Rain o et al 25 reported that thermally induced hole escape is the main non-radiative process which deteriorates the optical properties and performances of the GaSb-based devices at elevated temperature.…”

Direct evidence for suppression of Auger recombination in GaInAsSbP/InAs mid-infrared light-emitting diodes

“…A similar phenomenon has previously been observed in GaInAsSb lasers operating at 2.37 lm using high pressure techniques. 23 Since the spin-orbit split-off energy is largely controlled by the group V composition, it is relatively insensitive to pressure. Hydrostatic pressure also increases both m so and m e .…”

Band-structure and gain-cavity tuning of 2.4-µm GaSb buried tunnel junction VCSELs

“…Figure 1 shows the pressure dependence of the threshold current, I th , of the VCSEL at three different temperatures (-10ºC, 20ºC and 30ºC) and of a reference EEL with the same active region (I th in this case normalised to its value at atmospheric pressure). The decrease in I th with increasing pressure in the EEL indicates that Auger recombination is dominant at room temperature in this materials system and explains the temperature sensitivity of these EELs [3]. In the VCSEL the pressure dependence of I th is much more complicated.…”

“…In this work we have used high pressure techniques to investigate ways to improve their performance and extend their working temperature range. Since the band-gap and energy of the gain peak (E p ) increase with pressure at 0.126 meV/MPa [2] at constant temperature, when applied to edge emitting lasers (EEL) we can use pressure to determine the radiative and non-radiative recombination processes occurring [3]. In VCSELs, the pressure also tunes E p relative to the cavity mode energy E cm , which has a much weaker pressure dependence.…”

“…One promising approach to cover the spectral range between 2 and 3 µm, where several pollutant gases such as CO, CO 2 , CH 4 and NH 3 have strong absorption lines, is the development of GaSb-based inter-band lasers. Low-cost, continuous-wave GaSb-based vertical cavity surface emitting lasers (VCSELs) operating at ~2.4 µm up to 50ºC have been demonstrated recently [1].…”