Metalorganic molecular beam epitaxy of AlGaAs using APAH

To take advantage of the benefits of gaseous precursors for the growth of AlGaAs, a reduction of the carbon and oxygen uptake from the sources is necessary. Therefore, new precursors have been developed recently to overcome these problems. An entirely new approach is the use of an intramolecular saturated precursor, where the coordinative saturation against oxygen is realised by means of a double ring structure. 1-(3-dimethylaminopropyl)-1-ala-cyclohexan (APAH) is a representative of this class of precursors. In metalorganic molecular beam epitaxy (MOMBE) the suitability of APAH for the growth of AlxGa1-xAs layers (0 &lex&le1) was investigated in combination with TEGa and arsine. For the grown layers morphology and crystallinity are found to be excellent, whereas the background carrier concentrations are in the range of p=1017 to 1019 cm-3. SIMS measurements clearly identify carbon as the main acceptor. Other than carbon, nitrogen is also incorporated from APAH. Despite this, APAH is useful for particular heterostructure applications as demonstrated by quantum well structures with excellent interfaces. Therefore, in MOMBE of AlGaAs, APAH is a suitable Al precursor for applications where p-type doping of 1017 cm-3 or above is required or acceptable (e.g., in HBT).