Growth of resonant-cavity enhanced photodetectors by MBE with in situ feedback control using spectroscopic ellipsometry

Precise control of layer thickness and alloy compositions are very critical for the successful growth of vertical cavity surface emitting lasers (VCSEL) and resonant cavity enhanced photodetectors (RCEPD). In traditional MBE, the growth of these devices requires extensive calibrations. Recently, spectroscopic ellipsometry (SE) was shown to be an accurate method for determining the composition and thicknesses of III–V semiconductor layers in situ during growth. This paper reports the growth of AlAs/GaAs/InGaAs RCEPDs using SE control with no a priori calibration curves. The experimentally measured cavity resonance of the reflectivity spectrum and the photoresponse peak of the fabricated photodiode lie within 3 nm of the target design value of 990 nm. These results show that feedback control during MBE allows quicker and more reproducible growth of RCEPDs with precise control of layer thickness and alloy composition than calibration-based control.