Laytec improves nk database
InP based materials exhibit higher electron mobility and higher frequency response compared to GaAs. This makes InP HBTs a good candidate for next generation transimpedance amplifiers in optical fibre communications and 5G applications, notes metrology company Laytec.
Moreover, since InP HBT's base bandgap energy is much lower than that of GaAs HBTs, the InP based device's turn-on voltage and related power consumption are significantly lower.
However, the high-yield MOCVD growth of device grade quaternary InGaAsP and InGaAlAs structures precisely lattice-matched to InP is rather challenging, especially on larger wafers. According to Laytec, the solution is in-situ process control based on accurate high temperature quaternary nk data.
Working with Tony Spring Thorpe's team at National Research Council of Canada and Christoph Hums and his co-workers at Fraunhofer HHI Berlin (Germany), LayTec has now further improved the accuracy level of its nk database for the two quaternary material systems InGaAsP and InGaAlAs.
Figure a) shows the 633 nm refractive index of InG-aAsP and InGaAlAs in the full composition range at three relevant growth temperatures T1