M.Sc Thesis

M.Sc StudentShvartzman Mark
SubjectPassivation of InP and InP-Based Devices by Organic Self-
Assembled Monolayers
DepartmentDepartment of Chemical Engineering
Supervisors PROF. Yaron Paz
PROF. Dan Ritter


Passivation of InP and its devices by organic self-assembled monolayers (SAMs) of organic thiols is presented.  SAM’s on InP were characterized by FTIR, contact angle measurements and Auger spectroscopy.  It was found that the intensity of steady state photoluminescence (PL) of n-type InP wafers covered with the thiolated SAMs was significantly higher than that of bare wafers.  Furthermore, the dark current in I-V curves of metal-semiconductor-metal (MSM) diodes fabricated on semi-insulated InP was one order of magnitude smaller for diodes coated with the ultrathin layers.  Similarly, a reduction by several orders of magnitude in the leakage current of p-i-n avalanche photodiodes (APD) was observed upon coating. The enhancement in photoluminescence intensity upon covering the surface with thiolated SAMs, as well as the reduction in the dark current of the devices, is explaned in terms of the reduction in the density of surface states due to electrical passivation.  The ease by which one can tailor the outer functional groups of SAM’s provides a way to connect this new class of passivators with standard encapsulators, such as polyimide, as demonstrated by the wetting properties of modified surfaces. The passivating properties of thiolated SAM, formed on InP surface and covered by well wetted polyimide layer, was found to be stable at the relatively high temperature, at which the polyimide is cured. In this way a possible compatibility between passivation by thiolated SAMs and existing encapsulation process of InP devices was examined