Abstract
Displaying a full or tuneable emission spectrum with highly efficient is significant for luminescent materials used in solid-state lighting. Silicon carbide (SiC) has potential for use in photoelectric devices that operate under extreme conditions. In this paper, we present a method to selectively modify the photoluminescence (PL) properties of SiC by ultrafast laser direct writing. Based on this method, visible white PL could be observed by the naked eye at room temperature under ultraviolet excitation. By increasing the laser power intensity from 40 to 80 MW/cm2, the PL of the irradiated samples increased and pure white sunlight-like emission with controlled colour temperature was realised. The optimised laser power intensity of 65 MW/cm2 achieved a desirable colour temperature similar to that of sunlight (x = 0.33, y = 0.33 and colour temperature of 5500 K) and suppressed blue emission. By direct laser irradiation along designed scanning path, a large-scale and arbitrary pattern white emission was fabricated. The origin of the white luminescence was a mixture of multiple luminescent transitions of oxygen-related centres that turned the Si-C system into silicon oxycarbide. This work sheds light on new luminescent materials and a preparation technique for next-generation lighting devices.
Highlights
Displaying a full or tuneable emission spectrum with highly efficient is significant for luminescent materials used in solid-state lighting
Higher power intensity resulted in material ablation but not the formation of hemispheres based on the balance between the expansion and deposition of the plasma
By increasing the laser power intensity from 40 to 80 MW/cm[2], the PL of the treated surface turned from yellowish white to pure white to bluish white, the emission colour shifted to bluish white and the colour temperature quickly increased from 4193 K to a maximum of 8224 K
Summary
Displaying a full or tuneable emission spectrum with highly efficient is significant for luminescent materials used in solid-state lighting. We present a method to selectively modify the photoluminescence (PL) properties of SiC by ultrafast laser direct writing Based on this method, visible white PL could be observed by the naked eye at room temperature under ultraviolet excitation. Owing to the achievement of highly efficient group III nitride-based blue light-emitting diodes (LEDs), white LEDs that are based on blue LED excitation of yellow phosphor coatings that contain rare-earth elements are commonly used for lighting applications Such an emission spectrum composition with excess blue component leads to a low colour-rendering index of up to 68 and high colour temperature of 7400 K, increasing the risk of ‘blue hazard’. By direct laser irradiation along a designed scanning path, a large-scale, arbitrary pattern displaying selective visible white light emission is fabricated. A laser-fabricated p-n junction is produced, showing the potential to fabricate semiconductor devices with rectifying properties
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