Noncontact interface trap determination of SiO2–4H–SiC structures

Abstract

A sequence of noncontact corona-Kelvin metrology is introduced that enables the determination and monitoring of interface properties in dielectric/wide band gap semiconductor structures. The technique involves the incremental application of precise and measured quantities of corona charge, QC, onto the dielectric surface followed by determination of the contact potential difference, VCPD, as the material structure response. The V-Q characteristics obtained are used to extract the surface barrier, VSB, response related to the applied corona charge. The described approach differs from the common noncontact method applied in the case of dielectric/silicon structures where for each quanta of applied charge the value of surface barrier voltage, VSB, is obtained. Materials with wide band gaps and high concentrations of deep levels, as suggested for silicon carbide, do not permit quick determination of VSB by modulation of the band bending in the semiconductor with light. Light exposure in the case of SiC results in a long recovery time required to approach the nominal value of the preillumination VCPD value. The metrology approach presented determines an intersection of the VCPD-QC characteristic obtained in the dark with the Vox-QC characteristic representing the dielectric response. The specific VSB-QC dependence surrounding the reference VFB value is obtained from this approach and enables the noncontact determination of the dielectric interface trap density and its spectrum. Application of the modified metrology method to thermal oxide on n-type 4H-SiC demonstrates the modification of the Dit distribution by Fowler–Nordheim stress. In addition, an ability to quantify and separate trapped charge components is shown.

Method for noncontact measurement of 2DEG mobility and carrier density in AlGaN/GaN on semi-insulating wafers

“…The corona charge-bias method was originally designed for corona charge-Kelvin voltage metrology, extensively used in the silicon IC industry. [1][2][3] Later, it was extended to wide bandgap semiconductors, such as SiC, 4) GaN, and AlGaN/GaN. 5) A version of the technique known as corona noncontact C-V 5) was employed in previous research on the characterization of AlGaN/GaN heterostructures and 2DEG in the "normally on" HEMT configuration.…”

Review—Recent Advancement in Charge- and Photo-Assisted Non-Contact Electrical Characterization of SiC, GaN, and AlGaN/GaN HEMT

“…For historical reasons, one shall point out that the Q 2 -V method was used in the very first non-contact corona-Kelvin measurement of dopant concentration in SiC reported by E. Oborina and A. Hoff. 25 The corona-Kelvin C-V results for a GaN n-type epitaxial layer are shown in Fig. 6.…”

Application of Corona Charge Deposition Technique in Thin Film Industry

“…The semiconductor surface barrier potential, Vs, separate from the dielectric potential is determined/ measured. For oxides on SiC [56] [57], this metrology has been applied to the determination of the capacitance-voltage dependence, World Journal of Nano Science and Engineering and Fowler-Nordheim characteristics of as grown dielectrics [58]. Tunneling due to substrate emission in oxide films on silicon can be accomplished by biasing the structures; with deposited corona ions and measuring the resulting potential decay with a Kelvin probe [59] [60].…”