Abstract

Positron lifetime measurements are used in combination with electrical(Hall and resistivity) investigation to study na­tive point defects and their complexes in as-grown GaAs crystals. We explained the characteristic of the defects in GaAs.The life­time spectra measured in different positions on the GaAs slice are not one-component spectra,but they can be well fitted by th­ree exponentials.The vacancy concentration observed by us gives an underestimate of the deviation $ from the stoichiometry.Con­centration of divacancy(I2) as well as EPD variation along the radial of the slice takes W-shape profile,while the concentration of nonovacancy or/and complexes of monovacancy with impurities takes K-shape profile.EPD as well as multi-vacancy clusters is closely related with the deviation s from the stoichiometry(melt composition)•