Photochemical etching of n-InP: temperature, power and frequency studies

Photochemical (PC) etching of n-InP using an Ar/sup +/ laser and dilute phosphoric acid solutions was studied as a function of temperature, power, illumination frequency, and duty cycle. The process was found to be reaction-rate limited with an activation energy >or=0.34 eV. The photo-etch rate, i.e. the etch rate divided by the fraction of time the Ar/sup +/ light is on, was found to be a function of the illumination duty cycle but not the chopping frequency in the range 100-3200 Hz. These results are explained on the basis of a rate equation model for material removal. An application for PC etching is presented in which n-InP wafers 35-200- mu m thick were prepared for observation in the transmission electron microscope.<>