| AVS 66th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF+EM-WeA |
| Session: | Emerging Thin Film Materials: Ultra-wide Bandgap and Phase Change Materials |
| Presenter: | Fikadu Alema, Agnitron Technology, Inc. |
| Authors: | A. Osinsky, Agnitron Technology, Inc. F. Alema, Agnitron Technology, Inc. Y. Zhang, University of California, Santa Barbara A. Mauze, University of California, Santa Barbara J.S. Speck, University of California, Santa Barbara P. Mukhopadhyay, University of Central Florida W. Schoenfeld, University of Central Florida |
| Correspondent: | Click to Email |
We report on the growth of device quality β-Ga2O3 and related alloys using MOCVD method. β-Ga2O3 thin films are grown using Ga(DPM)3, TEGa and TMGa as Ga sources, and molecular O2, H2O vapor, and N2O as an oxidizer. Films grown from each Ga source had high growth rates with up to 10 m/hr achieved using TMGa [1]. The effect of the oxidizer identity on the growth rate, electron mobility (µe), background carrier concentration, surface and crystalline quality of the films will be discussed. Using pure O2 as an oxygen source, optimal growth conditions have led to the growth of smooth epitaxial UID Ga2O3 thin films with a RT µe of 176 cm2/Vs at n~7x1015 1/cm3 [2]. The highest µe of ~3500 cm2/Vs has been measured at 54 K. C and H impurities have been shown to be below the SIMS detection limit for a wide range of process conditions, whereby films with n~ 2x1014 cm-3 were demonstrated. We will also present the growth of device quality β-Ga2O3 layers doped with Si, Fe, and N impurities. Critical growth conditions influencing the incorporation of these dopants will be discussed. Using optimum growth conditions, controllable doping with a concentration between 1015 and 1020 1/cm3 were obtained for each dopant. In this work, we will also present on the MOCVD growth of (Alx, Ga1-x)2O3 alloys. The MOCVD process enables the growth of AlGaO at a temperature >800 oC, improving the solubility of Al2O3 in β-Ga2O3 by preventing the formation of volatile suboxides. The MOCVD reactor used in this work has a unique feature that enables it to minimize premature reaction between the species, thereby improving the Al incorporation. AlGaO alloys with Al content of up to 43 % was obtained. The epitaxial growth of high quality strained β-(Al, Ga)2O3/Ga2O3 heterostructures and superlattices will be discussed. The composition homogeneity, structural quality, surface morphology and electrical properties of the heterostructures will be discussed as a function of growth conditions. Finally, the growth of alloys including β-(In, Ga)2O3 and ZnGaO using MOCVD and their application for photodetection purposes will be discussed.
[1] F. Alema et al., J. Cryst. Growth, 475, 77(2017).
[2] Y. Zhang et al., APL Materials, 7, 022506 (2019).