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 sourc es is necessary. Therefore, new precursors have been developed recentl y to overcome these problems. An entirely new approach is the use of a n intramolecular saturated precursor, where the coordinative saturatio n against oxygen is realised by means of a double ring structure. 1-(3 -dimethylaminopropyl)-1-ala-cyclohexan (APAH) is a representative of t his class of precursors. In metalorganic molecular beam epitaxy (MOMBE ) the suitability of APAH for the growth of AlxGa1-xAs layers (0 less- than-or-equal-to x less-than-or-equal-to 1) was investigated in combin ation with TEGa and arsine. For the grown layers morphology and crysta llinity are found to be excellent, whereas the background carrier conc entrations are in the range of p=10(17) to 10(19) cm-3. SIMS measureme nts clearly identify carbon as the main acceptor. Other than carbon, n itrogen is also incorporated from APAH. Despite this, APAH is useful f or particular heterostructure applications as demonstrated by quantum well structures with excellent interfaces. Therefore, in MOMBE of AlGa As, APAH is a suitable Al precursor for applications where p-type dopi ng of 10(17) cm-3 or above is required or acceptable (e.g., in HBT).