Modelling of Kelvin probe surface voltage and photovoltage in dielectric-semiconductor interfaces

The characterisation of dielectric-semiconductor interfaces via Kelvin probe surface voltage and photovoltage has become a widespread method of extracting the electrical properties influencing optoelectronic devices. Kelvin probe offers a versatile, contactless and vacuum-less technique able to provide useful insights into the electronic structure of semiconductor surfaces. Semiconductor theory has long been used to explain the observations from surface voltage measurements, often by making large assumptions about the characteristics of the system. In this work I report an updated theoretical treatment to model the results of Kelvin probe surface voltage and photovoltage measurements including four critical mechanisms: the concentration of charge stored in interface surface states, the charge stored in different locations of a surface dielectric thin film, the changes to effective lifetime and excess carrier density as a result of charge redistribution, and the non-uniformity of charge observed on most large scale thin film coatings used for passivation and optical improvement in optoelectronic devices. A full model is drawn and solved analytically to exemplify the role that these mechanisms have in surface voltage characterisation. The treatment in this work provides crucial understanding of the mechanisms that give rise to surface potential in semiconductors. As such this work will help the design and development of better optoelectronic devices.

Automated summary

Characterising dielectric-semiconductor interfaces using Kelvin probe surface voltage and photovoltage has become a widely adopted method for evaluating the electrical properties of optoelectronic devices. This work presents an updated theoretical treatment that incorporates four critical mechanisms to model the results of these measurements. By considering the charge concentration in interface surface states, charge distribution in different locations of a surface dielectric thin film, changes in effective lifetime and excess carrier density due to charge redistribution, and the non-uniformity of charge observed on large scale thin film coatings, the model provides crucial insights into the mechanisms underlying surface potential in semiconductors. This understanding can greatly contribute to the design and development of improved optoelectronic devices.