Molecular Beam Epitaxy

Molecular Beam Epitaxy (MBE) is a deposition technique commonly used for compound semiconductor growth. It has widespread use in R&D labs, but also in commercial applications such as GaAs and InP-based Heterojunction Bipolar Transistors (HBTs). In my lab, I am working on refurbishing a Varian MOD Gen II MBE chamber. We received the system from a fellow university lab, but it has needed a bit…

Liquid Phase Epitaxy

Liquid phase epitaxy (LPE) is a crystal growth technique that dates back to the 1960s. Although seldom used today, LPE was the enabling technology for many of the most critical compound semiconductor technologies that are still prevalent today (including the AlGaAs/GaAs heterojunction bipolar transistor, high efficiency solar cells, CW lasers, and LEDs). While much of the industry and research work in compound…

III-V MIS Solar Cells

While the vast majority of solar cells use a p-n junction to induce the photovoltaic effect, alternative designs using a metal-semiconductor (MS) junction may be relevant for certain applications, including wide band gap solar cells or low-cost III-V-based thin film devices. Prior to modern epitaxial growth systems, nearly all PV devices were fabricated by diffusing dopants into a semiconductor at high temperatures….

Nonisovalent Alloys

Visible wavelength optoelectronic devices, including solar cells, photodetectors, and light emitting diodes (LEDs), predominantly use isovalent compound semiconductors of the form (AB)y(CD)1-y where AB and CD are binary compounds of the same valency, meaning a III-V mixed with another III-V (e.g., GaAs-AlAs, GaP-InP), or a II-VI with a II-VI (e.g., HgTe-CdTe, CdTe-ZnTe). Combining these various elements in alloy form lends to characteristic…