Speaker
Description
The optical properties of InAsxP1-x metamorphic buffers grown by metal-organic chemical vapor deposition (MOCVD) on InP substrates have been investigated. From photoreflectance spectrum, the optical bandgap energy shows around the 0.81 eV, 0.72 eV, and 0.61 eV with As composition x= 0.5,0.55, and 0.7, respectively. Furthermore, the Franz-Keldysh oscillation (FKO) signal shown above at InAsxP1-x bandgap energy, can calculate the internal electric field (F) by Fast-Fourier transform (FFTs) methods. All samples have three main peaks around of 15 eV-3/2 to 130 eV-3/2 as a result of FFT. From the result of calculation F, x= 0.5 and 0.7 samples have similar F values, and the 0.55 sample shows a lower F value by about 70 kV/cm. It is caused by the defect density, which increases the probability of photo-generated carrier trapping. The higher the defect density at the interface, the lower the carrier density decreases, which reduces the photovoltaic effect.
