Grown-in defects in multi-epilayer GaAs grown by metalorganic chemical vapor deposition under different growth conditions

Studies of the grown-in defects in multi-epilayer GaAs (with/without a buffer layer) grown by metalorganic chemical vapor deposition under different [AsH3]/[TMGa] ratios, growth temperatures, and growth rates have been made in this letter by the deep level transient spectroscopy method. For samples without a buffer layer, two electron traps with activation energies of Ec−0.83 eV (EL2a) and Ec−0.74 eV are observed, whereas for samples with 6-μm-thick buffer layers, only EL2a level is found. The concentration of the deep level traps is found closely related to the [AsH3]/[TMGa] ratio, the growth temperature, and the growth rate (mainly at lower growth rate). The results show that, for samples without a buffer layer, the background dopant density profile is closely related to the deep level trap density profile in the epilayers, whereas for samples with a buffer layer, the profile of background dopant density is less influenced by the presence of the deep level trap.