Researchers at Lund University used diamond to effectively dissipate heat from a perovskite laser

In the development of CW laser from femtosecond pulse laser perovskite laser has taken a key step towards electric laser excitation. After the CW laser at ambient temperatures, building an electrically driven laser is the next goal.

Conventional epitaxial production of single crystal semiconductors with large thermal conductivity κand high charge carrier mobility m usually in commercially available electroinjection lasers in large current show small resistance heating. Perovskite has a low κvalue and a large and balanced carrier mobility.

Compared with GaAs with thermal conductivity of 50 W m -- 1 K -- 1, the thermal conductivity of MAPbI 3 is only 1 -- 3 W m -- 1 K -- 1. As a result, heat generated due to energy loss by non-radiative pathways cannot be properly dispersed.

Due to the dilution of the particle population inversion for any given transition and other problems such as degradation and heat-induced defects, this failure will raise the laser threshold as carriers occupy a wider energy range at higher temperatures. The lowest electrical excitation threshold of distributed feedback (DFB) perovskite laser can reach 24 mA cm-2.

External quantum efficiency can also be severely limited in high current injection Settings due to Joule heat in conventional perovskite LED designs used in laser systems. Therefore, thermal control is an obstacle to the development of electric perovskite lasers.

In this context, a research team led by Professor Zheng Kaibo from Lund University and Professor Li Guohui from Taiyuan University of Technology demonstrated on a diamond substrate a perovskite nanosheet laser that can effectively dissipate the heat generated during the optical pumping process. The displayed laser has a Q factor of about 1961 and a laser threshold of 52.19 μJ cm -- 2.

The addition of a thin SiO 2 gap layer between the nanosheet and the diamond substrate also results in tight optical limitations. The electric field distribution within the structure indicated that a wide SiO 2 gap with a thickness of 200 nm significantly reduced the leakage field in the diamond substrate, and also indicated that the mode limitation in MAPbI 3 nanosheets was improved.

The thermal dissipation of perovskite nanosheet laser on diamond substrate is measured by temperature variation under optical pumping.

Due to the inclusion of a diamond substrate, the laser has a low pump density dependent temperature sensitivity (~0.56 ± 0.01 K cm -- 2 μJ-1). The sensitivity is one to two orders of magnitude lower than previously reported values for perovskite nanowire lasers on glass substrates.

Nanosheet lasers can operate at high pumping densities due to the high thermal conductivity of diamond substrates. The research can provide inspiration for the creation of electric perovskite lasers. The work is published in SCIENCE CHINA Materials.

Source: Laser Net