Layer perfection in ultrathin MOVPE-grown InAs layers buried in GaAs(001) studied by X-ray standing waves and photoluminescence spectroscopy

Using the In-L fluorescence produced by normal-incidence X-ray standing wav es, we have measured the layer perfection and positions of 1 and 1/2 monola yer (ML) InAs quantum wells buried in GaAs(001). Growth temperature effects were studied in a series of samples produced by metalorganic vapor phase e pitaxy (MOVPE) at temperatures between 400 and 600 degrees C. The coherent position of the In atoms decreases with temperature in the 1 ML samples, an d the optimal growth temperature is near 550 degrees C, as evidenced by the coherent position of 1.15+/-0.02, and the relatively high coherent fractio n of 0.72+/-0.08. These results are corroborated by 1.6 K photoluminescence (PL) measurements in which the most sharp and intense In-excitonic emissio n is obtained from a sample grown at 530 degrees C. For the 1/2 ML samples, growth temperatures of 400 degrees C and 600 degrees C produce similar sta nding wave results: coherent positions of 1.09+/-0.02 and 1.10+/-0.02, cohe rent fractions of 0.75+/-0.10 and 0.74+/-0.11, respectively. However, PL re veals the higher temperature sample to be of far superior quality, due to e xcessive carbon incorporation at 400 degrees C.