Dislocations introduced in n-GaN at room temperature cause conductivity inversion

• Published in: Journal of alloys and compounds 2021-10, Vol.877, p.160281, Article 160281
• Main Authors: Yakimov, Eugene B., Vergeles, Pavel S., Polyakov, Alexander Y., Shchemerov, Ivan V., Chernyh, A.V., Vasilev, A.A., Kochkova, A.I., Lee, In-Hwan, Pearton, S.J.
• Format: Article
• Language: English
• Subjects: Basal plane; Cathodoluminescence; Deep level transient spectroscopy; Defect states; Dislocation density; Dislocations; Electrical impedance; Electrical measurement; GaN; Metalorganic chemical vapor deposition; Room temperature; Sapphire; Scratching; Spectrum analysis
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160281

•Dislocations are introduced into n-GaN at room temperature by scratching.•Measurement of the spatial properties show that dislocation introduction causes type conversion to high resistivity p-type conductivity.•We were able to measure the energy levels related to the dislocation-induced states.•Since dislocations can be introduced at room temperature, this means they can also be introduced during processing. Dislocations were introduced by scratching at room temperature of the surface of n-GaN films grown by Metalorganic Chemical Vapor Deposition (MOCVD) on basal plane sapphire. The dislocations were observed to propagate from the scratch along the directions along several slip systems and form a region with high dislocation density extending by 30–40 µm on each side of the scratch. The regions with enhanced dislocation density were characterized by a strong decrease of intensity of bandedge cathodoluminescence (CL) band at 368 nm, an emergence of the dislocation-related band at 400 nm wavelength, and a strong increase in intensity of the yellow CL band related to defects. Capacitance-voltage and current-voltage measurements in the dark and under illumination performed as a function of temperature indicates that the region with enhanced dislocation density is converted to p-type. Measurements of current versus temperature, admittance spectra, and Deep Level Transient Spectroscopy (DLTS) allowed for the first time to determine the energy position of dislocation-related acceptors level near Ev+ 0.35 eV and to estimate their concentration.