Low-resistance visible wavelength distributed Bragg reflectors using smallenergy band offset heterojunctions

Semiconductor alloy heterojunctions, with compositions selected to achieve small band offset energies, were used in distributed Bragg reflector (DBR) structures for the purpose of lowering the vertical series resistance. The heterojunctions were simple abrupt interfaces without composition grading. 40 period mirrors of AlGaInP/Al(Ga)As layer pairs were grown by gas-source molecular beam epitaxy. Mirror reflectance values were found to be greater than 99% at wavelengths near 650 nm. Measured specific resistance values, 2 .8x10(-4) Omega cm(2) for a p-type DBR and 2.6x10(-5) Omega cm(2) for a n-t ype DBR, were comparable to or better than (Al)GaAs/Al(Ga)As DBRs employing various graded interface composition designs. (C) 1999 American Institute of Physics. [S0003-6951(99)01125-0].