In situ observation of the strain in GaP on Si during cooling step after growth by Raman spectroscopy

Abstract

A new Raman measurement system with which it is possible to characterize various properties of semiconductors being grown in an atmosphere of flowing gas at a high temperature was developed. As an example of application of the system, the characterization of gallium phosphide (GaP) grown on a silicon (Si) substrate by chloride vapor phase epitaxy at 700 °C was done. The Raman spectra indicated that almost all the strain in a GaP layer with a thickness of 1 μm on a Si(111) substrate due to the difference of lattice constants is relaxed at the growth temperature while tensile strain due to the difference of thermal expansion coefficients exists at room temperature. The results of Raman spectra measured at every hundred degrees during the cooling process have good agreement with the calculated results based on the bimetal model. This means that thermal stress is stored gradually at the early stage of the cooling process.