Investigation of interfacial oxidation control using sacrificial metallic Al and La passivation layers on InGaAs (original) (raw)
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Effects of surface passivation during atomic layer deposition of Al2O3 on In0.53Ga0.47As substrates
Microelectronic Engineering, 2011
In this work we investigate the effect of different III-V surface passivation strategies during atomic layer deposition of Al 2 O 3 . X-ray photoelectron spectroscopy indicates that bare As-decapped and sulfur passivated In 0.53 Ga 0.47 As present residual oxides on the surface just before the beginning of the Al 2 O 3 deposition while the insertion of a Ge interface passivation layer results in an almost oxide free Ge/III-V interface. The study of the initial growth regimes, by means of in situ spectroscopic ellipsometry, shows that the growth of Al 2 O 3 on Ge leads to an enhanced initial growth accompanied by the formation of Ge-O-Al species thus affecting the final electrical properties of the stack. Alternatively, deposition on decapped and S-passivated In 0.53 Ga 0.47 As results in a more controlled growth process. The sulfur passivation leads to a better electrical response of the capacitor that can be associated to a lower oxide/semiconductor interface trap density.
The Journal of Chemical Physics, 2012
Formation of a contaminant free, flat, electrically passive interface to a gate oxide such as a-Al 2 O 3 is the critical step in fabricating III-V metal oxide semiconductor field effect transistors; while the bulk oxide is amorphous, the interface may need to be ordered to prevent electrical defect formation. A two temperature in situ cleaning process is shown to produce a clean, flat group III or group V rich InGaAs surface. The dependence of initial surface reconstruction and dosing temperature of the seeding of aluminum with trimethylaluminum dosing is observed to produce an ordered unpinned passivation layer on InGaAs(001)-(4 × 2) surface at sample temperatures below 190 • C. Conversely, the InGaAs(001)-(2 × 4) surface is shown to generate an unpinned passivation layer with a seeding temperature up to 280 • C. For both reconstructions, the chemical drive force is consistent with formation of As-Al-As bonds. The optimal seed layer protects the surface from background contamination.
Applied Physics Letters, 2010
The effect of the surface passivation with ex situ wet clean as well as insertion of an III-V in situ grown interlayer, on the HfO 2 / In 0.52 Al 0.48 As interface characteristics was investigated with capacitance/conductance measurements, and synchrotron radiation photoemission spectroscopy. A very thin aluminum oxide passivation layer grown after In 0.52 Al 0.48 As surface clean improves the In 0.52 Al 0.48 As metal-oxide-semiconductor characteristics compared to native oxide covered interface, giving an interface state density ͑D it ͒ 3.8ϫ 10 12 cm −2 eV −1 at 0.31 eV from conduction band edge. Furthermore, insertion of a thin In 0.53 Ga 0.47 As cap layer effectively prevented Al oxidation further improving electrical properties, such as frequency dispersion, hysteresis, D it ͑2.7ϫ 10 12 cm −2 eV −1 ͒ and capacitive equivalent oxide thickness.
ECS Journal of Solid State Science and Technology, 2014
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Japanese Journal of Applied Physics, 2010
The reduction of native oxides on an InAs surface using various wet and dry chemical treatments, including hydrochloric acid (HCl) treatment, sulfide treatment, and in situ trimethyl aluminum (TMA) treatment before the atomic layer deposition (ALD) of Al2O3 on InAs is studied. X-ray photoelectron spectrum (XPS) results show that the effect of surface cleaning by TMA was apparent almost after the first pulse but that TMA cleaning is not as effective as wet chemical surface cleaning. The combination of wet chemical treatment and TMA pretreatment is the most effective method for InAs surface cleaning, as indicated by the XPS analysis. Capacitance–voltage (C–V) and current density–voltage (J–V) characteristics on metal–oxide–semiconductor capacitance (MOSCAP) structures were also investigated to evaluate the Al2O3/n-InAs interface quality after different surface treatments, and the results are consistent with the XPS analysis.
Oxidation Properties of Al-Nanostructures on Si Surfaces
Physica Scripta, 2004
Al 2 O 3 is a dielectric material with a higher κ−value than SiO 2 and thus a potential gate insulator material in future generations of silicon based complementary metal-insulator-semiconductor devices. A recent report by Guha et al.
Journal of Applied Physics, 2015
We examine the electrical properties of atomic layer deposition (ALD) La2O3/InGaAs and Al2O3/La2O3/InGaAs metal-oxide-semiconductor (MOS) capacitors. It is found that the thick ALD La2O3/InGaAs interface provides low interface state density (Dit) with the minimum value of ∼3 × 1011 cm−2 eV−1, which is attributable to the excellent La2O3 passivation effect for InGaAs surfaces. It is observed, on the other hand, that there are a large amount of slow traps and border traps in La2O3. In order to simultaneously satisfy low Dit and small hysteresis, the effectiveness of Al2O3/La2O3/InGaAs gate stacks with ultrathin La2O3 interfacial layers is in addition evaluated. The reduction of the La2O3 thickness to 0.4 nm in Al2O3/La2O3/InGaAs gate stacks leads to the decrease in hysteresis. On the other hand, Dit of the Al2O3/La2O3/InGaAs interfaces becomes higher than that of the La2O3/InGaAs ones, attributable to the diffusion of Al2O3 through La2O3 into InGaAs and resulting modification of the L...
Oxidation of GaAs semiconductor at the Al2O3/GaAs junction
Atomic-scale understanding and processing of the oxidation of III-V compound-semiconductor surfaces are essential for developing materials for various devices (e.g., transistors, solar cells, and light emitting diodes). The oxidation-induced defect-rich phases at the interfaces of oxide/III-V junctions significantly affect the electrical performance of devices. In this study, a method to control the GaAs oxidation and interfacial defect density at the prototypical Al 2 O 3 /GaAs junction grown via atomic layer deposition (ALD) is demonstrated. Namely, pre-oxidation of GaAs with an In-induced c(8 Â 2) surface reconstruction, leading to a crystalline c(4 Â 2)-O interface oxide before ALD of Al 2 O 3 , decreases band-gap defect density at the Al 2 O 3 /GaAs interface. Concomitantly, X-ray photoelectron spectroscopy (XPS) from these Al 2 O 3 /GaAs interfaces shows that the high oxidation state of Ga (Ga 2 O 3 type) decreases, and the corresponding In 2 O 3 type phase forms when employing the c(4 Â 2)-O interface layer. Detailed synchrotron-radiation XPS of the counterpart c(4 Â 2)-O oxide of InAs(100) has been utilized to elucidate the atomic structure of the useful c(4 Â 2)-O interface layer and its oxidation process. The spectral analysis reveals that three different oxygen sites, five oxidation-induced group-III atomic sites with core-level shifts between À0.2 eV and +1.0 eV, and hardly any oxygen-induced changes at the As sites form during the oxidation. These results, discussed within the current atomic model of the c(4 Â 2)-O interface, provide insight into the atomic structures of oxide/III-V interfaces and a way to control the semiconductor oxidation.