2019年5月23日星期四

A technique for the growth of single crystal films of zinc sulphide on (100) gallium arsenide by radio frequency sputtering

Thin films of single crystal cubic zinc sulphide has been grown on (100) oriented gallium arsenide substrates by a radio frequency sputtering technique. The sputtering system is of novel design, being constructed to UHV standards and capable of producing oil-free ultraclean conditions during the sputtering process. A balanced RF oscillator drives the water cooled disc and annulus electrodes to which sintered powder ZnS targets are bonded with an indium-gallium eutectic. Highly ordered films are grown at rates of up to 100 nm h-1 at temperatures between 250 degrees C and 300 degrees C.


Source:IOPscience

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2019年5月9日星期四

A method for selective substrate removal from thin p-type gallium arsenide layers

A two-stage etching technique enables the substrates to be removed from thin p-type layers of gallium arsenide over large areas. An n-type 'blocking layer' is used to retard the etching front during the selective first stage and this is subsequently removed using a nonselective etch. Greater precision is offered by this method than by conventional etching techniques.


Source:IOPscience

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2019年4月30日星期二

Tunnel assisted hopping in neutron irradiated gallium arsenide

The resistivity against dose curve in neutron irradiated gallium arsenide shows an anomaly. At doses in excess of 1017 n cm-2 the resistivity decreases with dose. The temperature dependence of resistivity indicates that the mechanism of conduction at high doses is tunnel assisted hopping. Since the structural studies reveal that even at the highest dose the material remains substantially crystalline the tunnel assisted hopping is considered to occur via defect energy levels.


Source:IOPscience

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2019年4月25日星期四

Microscopic structure of the 90° and 30° partial dislocations in gallium arsenide

We performed a theoretical investigation on the atomic structure of {111} glide partial dislocations in gallium arsenide. The calculations were carried out using ab initio total energy methods, based on the density functional theory and the pseudopotential model. We addressed the microscopic structure of the 90° partial and the 30° partial dislocations. Our results show that the atomic configurations of the dislocation cores are similar to those proposed for the same dislocations in non-polar semiconductors. For the 90° partial, the double-period reconstruction is energetically more favourable than the single-period reconstruction. In addition, we computed the interaction of intrinsic defects with the dislocation cores.


Source:IOPscience

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2019年4月18日星期四

The effect of a stacking fault on the electronic properties of dopants in gallium arsenide

We performed a theoretical investigation on the effects of extended defects on the structural and electronic properties of dopant atoms in gallium arsenide. We observed that silicon impurities segregate at GaAs stacking faults. A Si atom at a Ga site in a stacking fault in either a neutral or a negatively charged state is energetically favourable as compared to a Si atom at a Ga site in a crystalline environment by as much as 0.2 eV. Additionally, a substitutional Si impurity in the negative charge state in a stacking fault has a distinct structure as compared to the same impurity in a crystal. The results suggest that the stacking fault may prevent the formation of metastable defects, such as DX centres.



Source:IOPscience

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2019年4月9日星期二

The study of influence of the gas flow rate to etched layer thickness, and roughness of the anisotropy field of gallium arsenide is etched in the plasma chemical etching process

In the experiments on the etched surface of gallium arsenide were performed. We studied the effect of BCl3 gas flow rate on the thickness of the etched layer. GaAs etching rate was: 537,4 nm/min 28,7 nm/min 2,6 nm/min, the values of the flow rate of BCl3 NBCl3 - 15, 10, 5 cc/min, respectively. The effect of BCl3 gas flow rate to the mean-square roughness of the etched surface. The influence of the anisotropy of the process on the geometry of the etched area. Revealed that the deflection angle for the samples treated with the working gas flow rate NBCl3 - 15 cc/min in the [110] direction was α [110] = 65,5° in direction [111] was α [111] = 45,58°. For samples treated with the working gas flow rate NBCl3 - 10 cc/min in the [110] direction was α [110] = 20,94° in direction [111] was α [111] = 11,37°. For samples treated with the working gas flow rate NBCl3 - 5 cc/min in the [110] was α [110] = 0,32° in direction [111] was α [111] = 0,21°. The results can be used to produce discrete diodes, heterojunction devices, and other results.


Source:IOPscience

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2019年4月3日星期三

Direct Bonding of Gallium Arsenide on Silicon

Direct bonding of gallium arsenide on silicon is studied. The technology is expected to enable the easy integration of gallium arsenide optoelectronic devices with silicon very-large-scale integrated circuits. The interface quality of n-GaAs/p-Si can be improved with a thermal annealing process. It is examined by the current-voltage characteristics of the n-GaAs/p-Si diode. The bonding strength was found to be sufficiently high and could "high enough to" withstand the subsequent grinding and polishing procedures of the bonded wafers.


Source:IOPscience

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