Analysis of recombination centers in (AlxGa1−x)0.5In0.5P quaternary alloys

We studied nonradiative recombination centers in undoped (AlxGa1−x)0.5In0.5Pgrown 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 × 10−10 cm2 and a hole capture cross section of 1 × 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.