Comparison of different etching methods on the morphology and semiconductor characters of black silicon

Femtosecond laser etching, deep reactive ion etching and metal-catalyzed chemical etching are used to fabricate black silicon. It has been found that the light absorption is significantly enhanced in the wavelength of 400 similar to 2200nm, in which the absorption in near infrared band of black silicon etched by femtosecond laser with SF6 has the highest value. It is observed that, however, the minority carrier lifetime of crystalline silicon is shortened to some extent, which can be adjusted and controlled effectively by depositing SiNx film to passivate the surface of black silicon. Finally, a PIN photodetector is manufactured based on black silicon and a higher responsibility of 0.57 A/W at 1060 nm is obtained compared to the PIN silicon photodetector without etching process.