Shula Chen, Mattias Jansson, Jan E. Stehr, Yuqing Huang, Fumitaro Ishikawa, Weimin M. Chen, Irina A. Buyanova
Published in Nano lett. 2017, doi: 10.1021/acs.nanolett.6b05097

Nanowire (NW) lasers operating in the near-infrared spectral range are of significant technological importance for applications in telecommunications, sensing and medical diagnostics. So far lasing within this spectral range has been achieved using GaAs/AlGaAs, GaAs/GaAsP and InGaAs/GaAs core/shell NWs. Another promising III-V material, not yet explored in its lasing capacity, is the dilute nitride GaNAs.

In this work we demonstrate, for the first time, optically pumped lasing from the GaNAs shell of a single GaAs/GaNAs core/shell NW. The characteristic ‘S’-shaped pump power dependence of the lasing intensity, with the concomitant line width narrowing, is observed, which yields a threshold gain, g_th, of 3300 cm-1 and a spontaneous emission coupling factor, β, of 0.045. The dominant lasing peak is identified to arise from the HE21b cavity mode, as determined from its pronounced emission polarization along the NW axis combined with theoretical calculations of lasing threshold for guided modes inside the nanowire. Even without intentional passivation of the NW surface, the lasing emission can be sustained up to 150 K. This is facilitated by the improved surface quality due to nitrogen incorporation, which partly suppresses the surface-related non-radiative recombination centers via nitridation.

Our work therefore represents the first step towards development of room temperature infrared NW lasers based on dilute nitrides with extended tunability in the lasing wavelength.

Chart of SHG/SFG wavelength och Nanowire lasing wavelength

Efficient lasers at the nanoscale

In this study, Mattias Jansson and collaborators have investigated how the localization of excitons in tiny lasers fabricated in so-called nanowire structures can affect their performance.

Record conduction-electron spin polarization achieved, exceeding 90% at room-temperature

Record conduction-electron spin polarization achieved, exceeding 90% at room-temperature

We demonstrated generation of conduction-electron spin polarization exceeding 90% at room temperature in InAs quantum dots via remote spin filtering - the highest value reported in any semiconductor by any approach.

Functional electronic materials

In the Functional Electronic Materials group, we conduct scientific research on various state-of-the-art materials.