ULTRAHIGH-VACUUM ATOMIC LAYER EPITAXY OF CD1-XMNXTE LAYERS GROWN ON ZNTE GAAS(100) SUBSTRATES - REFLECTION MASS-SPECTROMETRY STUDIES/

Simultaneous reflection mass spectrometry (REMS) and reflection high e nergy electron diffraction (RHEED) measurements of the surface kinetic and structural parameters, respectively, governing the UHV ALE growth of Cd1-xMnxTe films are reported. A set of six experiments have been performed. Three of them concerned Cd1-xMnxTe UHV ALE, and one Cd1-xMn xTe MBE growth. For comparison, one experiment was also performed conc erning UHV ALE of Cd1-xZnxTe and one concerning UHV ALE of CdTe, with two sequent cation deposition pulses. The REMS signals for Cd+ cations during the deposition and 'dead' times of the ALE cycle were measured . RHEED patterns were also recorded to control the surface reconstruct ion of the epilayer during different deposition stages of the ALE cycl e. An interesting phenomenon was observed in the REMS Cd+ signal behav iour during the ALE growth of Cd1-xMnxTe and Cd1-xZnxTe. It consists i n an evident increase of the intensity of this signal occurring in cas es when both cation elements (Cd + Mn or Cd + Zn) are impinging onto t he substrate surface simultaneously. These changes in Cd+ REMS signals (15% and 5% in the cases of Cd + Mn and Cd + Zn simultaneous depositi on, respectively) have been attributed to effects of mechanical impact s between 'hot' Mn and a bit 'cooler' Zn atoms with weakly bound 'cool ' Cd atoms which are thermally accommodated to the substrate surface. The same mechanism, namely mechanical impact of 'hot' Mn atoms with 'c ool' Cd atoms is believed to be responsible for the measured differenc es in chemical composition of the ternary compound Cd1-xMnxTe, when gr own by MBE (x = 0.4) or UHV ALE (x = 0.06), at the same growth paramet ers applied. (C) 1997 Elsevier Science S.A.