P-type Ge epitaxy on GaAs (100) substrate grown by MOCVD

• Published in: Applied surface science 2016-07, Vol.376, p.236-240
• Main Authors: Jin, Y.J., Chia, C.K., Liu, H.F., Wong, L.M., Chai, J.W., Chi, D.Z., Wang, S.J.
• Format: Article
• Language: English
• Subjects: Density; Dimers; epitaxy; Gallium; Gallium arsenide; Ge thin film; Ge/GaAs integration; Germanium; MOCVD; Pillars; Retarding; Substrates
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.03.016

[Display omitted] •The heterogeneous integration of p-Ge/GaAs by MOCVD indicates significance for the application in optoelectronic devices such as p-MOSFET, dual band photodetector, etc.•Many undesired pillar-structures were observed on the p-Ge epilayers and we found that the cause of the pillar-like structures was related to the Ge-Ga dimers formed during the growth.•We found that a GaAs substrate with fewer Ga or Ge danglings was helpful in suppressing the formation of the unwanted pillar-like structures and thus obtaining high quality p-Ge epilayers. In this work, Ga-doped Geranium (Ge) films have been grown on GaAs (100) substrates by metal-organic chemical vapor deposition (MOCVD). Undesired pillar structures have been observed on the epilayers prepared at relatively lower temperatures. Energy dispersive X-ray spectroscopy (EDX) indicated that the pillars are mainly consisted of Ga atoms, which is totally different from that of the Ge film. It was demonstrated that the pillar structures could be reduced by simply raising the growth temperature while keeping the other growth conditions unchanged. In this regard, the growth mechanism of the pillars was related to the Ge-Ga dimers formed during the growth of p-Ge films. By further studying the influence of a GaAs or Ge buffer layer on the growth of p-Ge layers, we found that the GaAs substrate with lower density of Ga or Ge dangling bonds was helpful in suppressing the formation of the undesired pillar structures.