Integrated multiple sensor controlled molecular beam epitaxy for high performance electronic devices

We report the application of sensor-controlled molecular beam epitaxy (MBE) to the development of integrated electronic devices, specifically heterojunction bipolar transistors (HBTs) and resonant tunneling diodes (RTDs), for high performance circuits on InP substrates. Of particular importance for the integration of RTDs into a high performance circuit architecture is control of peak current density, J(p), which depends exponentially on quantum barrier layer thickness (roughly a factor of 2 change in peak current density per monolayer). Using a combination of spectroscopic ellipsometry and photoemission oscillation sensors, we have developed a real-time control process for AlAs barriers in In(0.5)3Ga(0.47)As/AlAs/InAs RTDs with +/- 0.1 monolayer precision (+/- 7% in J(p)). Key process control capabilities for reproducible deposition of HBT device structures are substrate temperature control (based on absorption edge spectroscopy), and ternary alloy composition control (based on spectroscopic ellipsometry). We report here the successful integration of two distinct HBT structures with RTDs on InP. In the first case, we have demonstrated good yield and RF performance (f(t) > 75 GHz, f(max) > 150 GHz) from HRL's baseline Ga0.47In0.53As/Al0.48In0.52As HBTs integrated with RTDs in a stacked geometry. In the second case, we have demonstrated high DC gain (40-50), high breakdown voltages (> 4V), and good RF performance (f(t) > 100 GHz) from Al0.48In0.52As/GaAs0.5Sb0.5 HBTs integrated with RTDs using Research Triangle Institute's Symmetric Intrinsic Process.