Room-temperature laser operation of a Ga(In,As)/Ga(As,Bi)/Ga(In,As) W-type laser diode

The ongoing pursuit for laser device emitting in the near-infrared spectral region on GaAs substrates has led to various material systems and device concepts. Alloys containing dilute amounts of Bismuth are promising candidates due to the already substantial band gap shift when incorporating low molar fractions of Bi in the GaAs host lattice. However, devices emitting at technologically essential wavelengths of 1.3 and 1.55 mu m have yet to be demonstrated using this material system. Especially the non-equilibrium nature of the growth conditions required to grow the metastable material makes epitaxial growth with high molar fractions of Bi challenging. An alternate approach to reach the desired wavelengths exploits a type-II band alignment between two materials to push the emission wavelength further into the telecom bands. Here, room-temperature laser operation of the first type-II structure employing Ga(As,Bi) as hole confining layer and (Ga,In)As as electron confining layer is demonstrated. Sample growth is conducted by low-pressure metalorganic vapour phase epitaxy. Broad area laser devices are processed and characterized by electroluminescence measurements. A threshold current density of 3.86 kA/cm(2) and emission wavelength of 1037 nm are observed, showing this device concept's potential for future lasers in the telecom bands.