ANALYSIS OF RECOMBINATION CENTERS IN (ALXGA1-X)0.5IN0.5P QUATERNARY ALLOYS

We studied nonradiative recombination centers in undoped (AlxGa1-x)0.5In0.5P grown by metalorganic vapor phase epitaxy using transient capacitance spectroscopy. We found three deep energy levels, including a mid-gap level. We drew an equation to get a capture cross section for minority carriers, and obtained it using isothermal capacitance transient spectroscopy measurement. The mid-gap level had an electron capture cross section of 2 x 10(-10) cm2 and a hole capture cross section of 1 x 10(-15) cm2. The time constant of nonradiative recombination through the mid-gap level was found to be comparable to that of radiative recombination. We concluded that the mid-gap level is an effective nonradiative recombination center that reduces photoluminescence intensity.