Abstract
We report here an optically pumped deep UV edge emitting laser with AlGaN multiple quantum wells (MQWs) active region grown on AlN substrate by low pressure organometallic vapor phase epitaxy (LP-OMVPE) in a high-temperature reactor. The 21 period Al<sub>0.53</sub>Ga<sub>0.47</sub>N/Al<sub>0.7</sub>Ga<sub>0.3</sub>N MQWs laser structure was optically pumped using 193 nm deep UV excimer laser source. A laser peak was achieved from the cleaved facets at 280.3 nm with linewidth of 0.08 nm at room temperature with threshold power density of 320 kW/cm<sup>2</sup>. The emission is completely TE polarized and the side mode suppression ratio (SMSR) is measured to be around 14 dB at 450 kW/cm<sup>2</sup>.
Highlights
Since the first demonstration of laser diode (LD) on group III-nitride materials some 20 years ago, technology has significantly matured with the availability of high quality GaN and, recently, AlN substrates
This led to the demonstrations of high-performance laser diodes ranging from infrared to visible and down to the UV spectral regime claiming their applications in high-density data storage, spectroscopy, sterilization, chemical detection, communications, and manufacturing industry[1,2]
We report a 21-period 2 nm Al0.53Ga0.47N/6 nm Al0.7Ga0.3N MQWs optically pumped laser on bulk AlN substrate by low pressure organometallic vapor phase epitaxy (LP-OMVPE) in a high-temperature reactor[5,11]
Summary
Since the first demonstration of laser diode (LD) on group III-nitride materials some 20 years ago, technology has significantly matured with the availability of high quality GaN and, recently, AlN substrates. Kirste et al reported a 3-period 2.5 nm Al0.55Ga0.45N/AlN MQW laser at 267 nm with low threshold power density of 6 kW/cm[2] by reducing unintentional point defects in the active region through high supersaturation growth conditions for waveguide layer. The results show a dominant deep UV laser peak at 280.3 nm, with lasing threshold of 320 kW/cm[2] and lasing FWHM of 0.08 nm at room temperature Such a narrow spectral linewidth and low lasing threshold demonstrate high quality 21 QWs heterostructure growth. For the same heterostructure design, the optical mode confinement factor is stronger for 21 QWs with 18.51% for TE mode and 14.35% for TM mode respectively compared to 3 and 15-period QWs. Figure 5(b) shows the peak PL emission intensities of heterostructure designs with 3, 15 and 21 MQWs at different pumping power densities. A subsequent chemical mechanical polishing (CMP) process was performed to thin down the substrate to around 70 μm
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