Hf O 2 gate dielectric on (NH4)2S passivated (100) GaAs grown by atomic layer deposition

Abstract

The interface between hafnium oxide grown by atomic layer deposition and (100) GaAs treated with HCl cleaning and (NH 4 ) 2 S passivation has been characterized.Synchrotron radiation photoemission core level spectra indicated successful removal of the native oxides and formation of passivating sulfides on the GaAs surface. Layer-bylayer removal of the hafnia film revealed a small amount of As 2 O 3 formed at the interface during the dielectric deposition. Traces of arsenic and sulfur out-diffusion into the hafnia film were observed after a 450 o C post-deposition anneal, and may be the origins for the electrically active defects. Transmission electron microscopy cross section images showed thicker HfO 2 films for a given precursor exposure on S-treated GaAs versus the SLAC-PUB-12802 September 2007Submitted to Journal of Applied Physics 2 non-treated sample. In addition, the valence-band and the conduction-band offsets at the HfO 2 /GaAs interface were deduced to be 3.18 eV and a range of 0.87-0.97 eV, respectively. It appears that HCl+(NH 4 ) 2 S treatments provide a superior chemical passivation for GaAs and initial surface for ALD deposition.

Preparation of gallium nitride surfaces for atomic layer deposition of aluminum oxide

“…Initial measurements for GaN(0001) samples did not indicate the presence of sulfur on the surface as there was no detectable signal for the sulfur peaks or chemical shifts in the rest of the spectra. The use of (NH 4 ) 2 S is well documented on GaAs, 32,[36][37][38] so to more diffinitively show that the wet clean process was temporarily preventing surface reoxidation XPS measurements were performed on GaAs(001) samples which received the identical (NH 4 ) 2 S wet clean. Both samples were measured at room temperature immediately after loading into the chamber, and the results for the GaAs and GaN samples are shown in Fig.…”

“…The sulfur treatment is expected to prevent reoxidation in ambient during transfer to the vacuum ALD system consistent with experiments on InGaAs 30,31 and GaAs. 32 After each step, samples were rinsed in deionized water for 1 min and then dried in N 2 gas.…”

Synchrotron radiation photoemission spectroscopic study of band offsets and interface self-cleaning by atomic layer deposited HfO2 on In0.53Ga0.47As and In0.52Al0.48As

“…Sulfur passivation is not stable at high thermal budget process [12]. SRPES has large advantages in terms of high energy resolution and surface sensitivity.…”

“…In order to prevent defect formation and Fermi-level pinning, various surface passivation techniques such as Si or Ge passivation [9], sulfur passivation [12], Ga 2 O 3 (Gd 2 O 3 ) passivation [10] have been proposed and demonstrated. However, Si and Ge are incorporated as dopants in III-V semiconductor substrate and alter the doping profile.…”

“…In order to sustain a better gate capacitance scalability for metal-oxide-semiconductor (MOS) device application, high-k dielectrics have been deposited onto the III-V semiconductor substrates, such as GaAs and InGaAs [2][3][4][5][6][7][8][9][10][11][12].…”