MOVPE GROWN INP-YB LAYERS USING YB(IPCP)3 AS A NEW DOPING SOURCE

For the Yb-doping of MOVPE grown InP, we have synthesized and used for the first time tris(isopropylcyclopentadienyl)-Yb, Yb(IpCp)3. This compound with its melting point at 47°C can be used as a liquid doping source, thus improving the reproducibility of the evaporation compared to the commonly used solid precursors. The grown InP:Yb layers revealed high photoluminescence intensities of the Yb 4f lines, although the Yb concentrations measured by SIMS were only in the range of 1017 cm-3. This indicates the high crystal quality of our samples. Additionally, we have grown InP:Yb:S layers and InP:Yb/InP:S multilayer structures with thicknesses between 10 and 100 nm for each layer to study the dependence of the excitation and decay processes on carrier and impurity concentration. The photoluminescence intensity of the 4f emission decreases for high S concentration in InP:Yb:S samples, whereas in the multilayer structures the intensity is the same as in InP:Yb samples. Based on the assumption of a homogeneous carrier concentration throughout the whole multilayer structure, we believe that a direct interaction between Yb and S atoms is responsible for the decrease in the double-doped single layers. The lifetime of the excited 4f state of Yb3+ is 13 μs, regardless of carrier or Yb concentration. For the InP:Yb samples co-doped with S, a fast nonexponential decay was observed, a further indication of some Yb-S pair interaction. © 1990.