The influence of graphite boat material on the purity of LPE InGaAs

This paper describes the purity of LPE InGaAs layers grown in graphite boats, machined from various graphite materials. The influence of the material is clearly visible if the growth solution is sufficiently pure. Carrier concentrations n<2×l0¹⁵ cm^–3 and mobilities(77 K)> 38000 cm²/Vs are routinely achieved for suitable graphite materials already from the third run of a new large boat applying a prebake of only 15 h. Small boats yield even better results (n=0.5×10¹⁵ cm^–3 and(77 K)=49500 m²/Vs). The sticking of In-rich solutions to the graphite does not depend on the material but is solely dependent on the surface roughness. The problem of graphite particle abrasion is discussed.