The Deposition of Silicon on Single-Crystal Spinel Substrates

Single crystal silicon has been epitaxially grown on (100), (110), and (111) magnesium aluminate spinel. The Hall mobilities of films grown on (111) spinel were higher than similar resistivity films grown on (100) and (110) spinel. Typical values of mobility have been 200 cm 2 /v‐sec on 1 µm thick p‐type films and 300 cm 2 /v‐sec on 15 µm thick p‐type films of 0.1 ohm‐cm silicon. These mobility values represent 80–100% of the mobility expected on similar resistivity bulk silicon. The autodoping of the films by the substrate was measured and compared with the aluminum autodoping of silicon‐on‐sapphire films. Silicon grown on spinel was doped about an order of magnitude less than silicon‐on‐sapphire. The deformation of the film and substrate was found to be anisotropic and the silicon was under a compressive stress of 1 – 4 · 10 10 dynes / cm 2 .