A Study on Low Temperature Photoelectrochemistry to Directly Fabricate Nanocrystals on Si Wafer

Our research team conducted the research activity on porous formation by electrochemical etching from2009. In 2014, we found the inhibition of the formation of porous silicon by using He-Ne laser. We found toimpose on the P-type silicon wafer (wavelength: 633nm) irradiation, laser light irradiating region, leavingporous silicon etching rate greatly reduced to 1/1000. In 2016, our team found that infrared laser light tofree-carrier effect to suppress the etching. In this study, we plan to further select the infrared radiation of1310-1650 nm and reduce the temperature to freezing point 0°C. The feasibility of formation of subnanocrystals(~ 0.5 nm) by free-carrier effect and low-temperature effect is also discussed. This study notonly analyzes the activation energy, but also deduces the relationship between the etching rate and theactivation energy of the photoactivation. In addition, it is expected that the formation mechanism of theporous silicon can be explained by the inhibition mechanism. The etching of a deep well-like structure thatmakes the surface of the silicon crystal form a uniform pattern has not yet been accepted as an acceptedexplanation. For example, photoluminescence excites blue light with UV as the basis for the development ofsilicon-based blue-light laser elements. The research program will further explore the laser wavelength andpower parameters for inhibition of etching, in order to obtain nanoscale thickness (<100 nm) porous siliconlayer. The research project will further choice 830-1650 nm wavelength laser through the laser power, theetch rate and the control parameters of time, analyze the activation energy deduced etch rate relationshipbetween the activation energy and light passivation proposed uniform distribution of porous siliconformation of the state model to explain why the electrochemical etching enables the silicon surface to formpatterns of sharing deep structure (as yet been proposed). In addition to this study, there is a scientific theoryto be proposed here and to generate an advanced technology expected to extend the development of MEMStechnology may be substituted the development process and the remove the photoresist coating photoresiststeps in MEMS component production, shortening the process time and reduce costs, enables production of3D MEMS device, mechanical and electrical fabrication techniques produce some revolutionarybreakthrough. On the other hand the surface of the silicon quantum dots with nanometer grainscharacteristic-based if the thickness of porous layer is below 100 nm, can also develop as the application ofsilicon-based laser components.