Room-Temperature Lasing Action in GaN Quantum Wells in the Infrared 1.5 μm Region

Abstract

Large-scale optoelectronics integration is strongly limited by the lack of efficient light sources, which could be integrated with the silicon complementary metal-oxide-semiconductor (CMOS) technology. Persistent efforts continue to achieve efficient light emission from silicon in the extending the silicon technology into fully integrated optoelectronic circuits. Here, we report the realization of room-temperature stimulated emission in the technologically crucial 1.5 µm wavelength range from Er-doped GaN multiple-quantum wells on silicon and sapphire. Employing the well-acknowledged variable stripe technique, we have demonstrated an optical gain up to 170 cm -1 in the multiple-quantum well structures. The observation of the stimulated emission is accompanied by the characteristic threshold behavior of emission intensity as a function of pump fluence, spectral linewidth narrowing and excitation length. The demonstration of roomtemperature lasing at the minimum loss window of optical fibers and in the eye-safe wavelength region of 1.5 µm are highly sought-after for use in many applications including defense, industrial processing, communication, medicine, spectroscopy and imaging. As the synthesis of Er-doped GaN epitaxial layers on silicon and sapphire has been successfully demonstrated, the results laid the foundation for achieving hybrid GaN-Si lasers providing a new pathway towards full photonic integration for silicon optoelectronics.1 Driven by the strong need for cheap and integrable Si-based optoelectronic devices for a wide range of applications, continuing endeavors have been made to develop structures for light emission, modulation, and detection in this material system. Recent breakthroughs including the demonstration of a high-speed optical modulator in Si, 1-2 photodetectors 3 , and waveguides 4 have brought the concept of transition from electrical to optical interconnects closer to realization.However, the base for silicon photonics, namely, a group IV laser source, still has to be developed.Due to the relatively small and indirect band gap, silicon is a poor light emitter. Nevertheless, lasing devices based on Si have been demonstrated including Si-based impurity lasers, 5 a Raman laser, 6 Si nanocrystals, 7 nanopatterned crystalline Si, 8 GeSn alloy on Si, 9 Ge dots in Si, 10-11 and InGaAs/GaAs nanolasers grown on Si. 12 However, these prototype devices essentially lack the advantages associated with the silicon system by requiring an external pump laser source or function only at low temperatures. While room-temperature luminescence has been realized, 7, 13 population inversion and optical gain have been under discussion and fundamental problems remain.The incorporation of rare earth elements into semiconductor hosts gives rise to sharp, atomiclike and temperature independent emission lines under either optical or electrical excitation. [14][15][16][17][18] Er ions with intra-4f shell transitions from its first excited state ( 4 I 13/2 ) to the ground state ( 4 I 15/2 ) produce 1.5 µm emissio...

Observation of optical gain in Er-Doped GaN epilayers

“…An adjustable shield was placed on the top of the sample to control the excitation length up to 1000 µm. [17] To achieve lasing operation, an optical cavity has been created from both polished edges of the sample. Two converging lenses with focal lengths of 10 and 24 cm were used to collect the edge-emission.…”

“…Note that the lasing threshold in the GaN:Er epilayer is a few times higher compared to those from Er-doped GaN nanolayers in multiple quantum well GaN/AlN structures. [17,39] In these structures, the multiple quantum wells provide an enhancement of the quantum efficiency for the infrared (1.5-m) emission band through the strain engineering, and carrier/exciton quantum confinement effect. [17,39] To explore the gain coefficient from the peaks of PL emission, we have used the well-known VSL method.…”

“…Recently, we have reported a lasing action in GaN/AlN multiple quantum wells in the infrared 1.5 m region. [17] The lasing in this structure is only obtained in a small volume.…”

“…Er-doped GaN material exhibits a significant low degree of thermal luminescent quenching, and strong emission at RT under either electrical or optical excitation. [7,15,17] We have successfully prepared Er-doped GaN epilayer on Si (001) and sapphire substrates by metal organic chemical vapor deposition (MOCVD) with good crystallinity and high percentage of Er 3+ optical centers, resulting in predominant photoluminescence (PL) at RT. [18][19][20] These prior works have provided necessary base to achieve near-infrared RT lasers based on Er-doped GaN (GaN:Er) semiconductor material.…”

Telecommunication-Wavelength Lasing in Er-doped GaN Multiple Quantum Wells at Room Temperature

“…The Er-doped GaN multiple quantum wells samples were prepared by metal organic chemical vapor deposition (MOCVD) on a c-plane sapphire substrates and had excellent material qualities [13,14]. The X-ray diffraction and photoluminescence (PL) measurements indicated that GaN:Er epilayers have high crystallinity, without second phase formation, and exhibit a strong room-temperature emission at 1.5 µm with a low degree of thermal quenching [15].…”