AVS 57th International Symposium & Exhibition
    Thin Film Tuesday Sessions
       Session TF1-TuM

Paper TF1-TuM11
In-situ XPS and Half-Cycle Studies of Atomic Layer Deposited Al2O3 on Group-III Nitride Substrate for MOS-HEMT Applications

Tuesday, October 19, 2010, 11:20 am, Room Pecos

Session: ALD: Dielectrics for Semiconductors
Presenter: P. Sivasubramani, University of Texas at Dallas
Authors: P. Sivasubramani, University of Texas at Dallas
T.J. Park, University of Texas at Dallas
B.E. Coss, University of Texas at Dallas
S. McDonnell, University of Texas at Dallas
R.M. Wallace, University of Texas at Dallas
J. Kim, University of Texas at Dallas
Y. Cao, University of Notre Dame
D. Jena, University of Notre Dame
H. Xing, University of Notre Dame
Correspondent: Click to Email
Group-III nitride (III-N) technology has been widely used in optoelectronics, RF transistors and power switching due to a suitable bandgap, excellent transport properties, high breakdown field, low power losses, as well as the possibility of forming a heterojunction structure on low cost, large area substrate templates such as Si, sapphire, etc. [1] X-N alloy on Ga-N (where X = Ga, In, or Al) are expected to achieve high-speed switching performance due to a high carrier mobility of 2-D electron gas formed at the heterojunction interface. The introduction of a high-quality, ultrathin, atomic layer deposited (ALD) dielectric in between the metal and semiconductor has been shown to effectively decrease the diode leakage current without compromising the MOS-HEMT transfer characteristics. [2, 3] The evaluation of interfacial and bulk bonding configurations as a function of ALD dielectric growth parameters could provide valuable information for III-N device application. Therefore, in this work, we have investigated the growth, interfacial, and bulk properties of ALD Al2O3 dielectric on top of Ga-N on top of a low-cost sapphire template. Immediately after surface preparation, the samples were loaded in an ultra high vacuum (UHV) custom tool which has an integrated x-ray photoelectron spectroscopy (XPS), ALD, and a UHV transfer tube for in-situ analysis of ALD half-cycle reactions with the III-N substrate. The surfaces were pre-cleaned using atomic H cleaning and/or solvent-wet chemical cleaning. XPS of III-N substrates indicates that a small, higher oxidation state component, possibly a hydroxide or an oxynitride (e.g. Ga-O-N) exists on the as-grown surface. The hydroxide and residual carbon components on the clean substrate and during the half-cycle reactions are simultaneously monitored. Significant charging of the semiconductor during XPS is circumvented by using a doped substrate along with suitable charge references. ALD half-cycle studies of the TMA (tri-methyl aluminum)/water and TMA/O3 reactions on the III-N surface will be presented. References: [1] Phys. Status Solidi C 6, No. 6, 1361 (2009) [2] Appl. Phys. Lett. 86, 063501 (2005) [3] IEDM09-15