A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry.

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A Ge-stabilized tetragonal ZrO2 dielectric with a permittivity (κ) value of 36.5 has been obtained by annealing a ZrO2/Ge/ZrO2 laminate at 500 °C and it is a more reliable approach toward stabilizing a tetragonal ZrO2 film. However, metal-insulator-metal (MIM) capacitors with the sole tetragonal ZrO2 film as an insulator achieve a high capacitance density of 27.8 fF/μm2 at the price of a degraded quadratic voltage coefficient of capacitance (VCC) of 81 129 ppm/V2 and unacceptably high leakage current. By capping an amorphous La-doped ZrO2 layer with a κ value of 26.3 to block grain boundaries-induced leakage paths of the crystalline ZrO2 dielectric, high-performance MIM capacitors in terms of a capacitance density of 19.8 fF/μm2, a VCC of 3135 ppm/V2, leakage current of 6.5×10−8 A/cm2 at −1 V, as well as a satisfactory capacitance change of 1.21% after ten-year operation can be realized.

A Ge-stabilized tetragonal ZrO2 (t-ZrO2) film formed by incorporating Ge atoms thermally driven from an underlying Ge layer into a ZrO2 film was investigated as the gate dielectric for Ge metal-oxide-semiconductor (MOS) capacitors fabricated on a Si substrate. A sole t-ZrO2 film on Ge is not eligible for the gate dielectric because of the poor interface quality. By using a thermally-grown ultrathin GeO2 film as an interfacial layer, the t-ZrO2/GeO2/Ge stack shows improved interface characteristics and a permittivity (κ) value of 36.6 for the t-ZrO2. In addition, the stack also demonstrates good leakage current since the amorphous GeO2 layer terminates grain boundary channels in the crystalline ZrO2. Further leakage current suppression can be achieved by a H2 annealing of the t-ZrO2/GeO2/Ge stack since the defects at grain boundaries can be effectively passivated, which makes a leakage current of 1.08×10−6 A/cm2 at VFB−1 V for effective oxide thickness of 1.66 nm and paves an alternative avenue to develop a high-performance crystalline gate dielectric for Ge MOS devices.

CF4 plasma treatment on germanium (Ge) surface is proposed in this work to alleviate the strong Fermi level pinning between metal/Ge, and its effectiveness is also explored for n- and p-type Ge wafers. It is found that samples with CF4 plasma treatment reveal conduction behavior transition between Schottky and ohmic characteristics, a metal-work-function-dependent Schottky barrier height as well as modulated contact resistance, and these results confirm the depinning of Fermi level. This depinning can be explained by the effective capability in passivating dangling bonds at Ge surface through fluorine atoms and the formation of Ge-F binding with partial ionic property, both of which are helpful in decreasing the number of surface states and consequently release the pinning effect.