Thickness Of AlxGa1 Research Articles

Optimal control of AlAs oxidation via digital alloy heterostructure compositions

A thorough study of wet thermal oxidation in AlAs/AlxGa1−xAs superlattices is presented. The results shown here demonstrate that the final oxidation depth can be finely tuned via the composition and thickness of AlxGa1−xAs into the digital alloy. A complete model of oxidation in these structures is proposed, relying on diffusion through the AlAs layer, its oxidation and an additional effect due to the AlxGa1−xAs intermediate barriers. This barrier contribution is shown to further improve the control of the oxidation rate, and thereby fabrication of sophisticated AlOx/GaAs integrated optoelectronic devices.

Comprehensive study of InGaP–AlxGa1−xAs–GaAs composite-emitter heterojunction bipolar transistors with different thickness of AlxGa1−xAs graded layers

The characteristics of InGaP–AlxGa1−xAs–GaAs composite-emitter heterojunction bipolar transistors (CEHBTs) with different thickness of AlxGa1−xAs graded layer are comprehensively studied and demonstrated. The thickness of the graded AlxGa1−xAs layer is an important factor to affect device performances. In this work, it is found that CEHBTs with 70 Å∼100 Å AlxGa1−xAs graded layers exhibit better properties due to the absence of potential spike. For comparison, experimentally, two practical CEHBTs with 0 and 100 Å AlxGa1−xAs graded layers are fabricated. Generally, good agreements between experimental results and theoretical simulations are found. It is, therefore, concluded that the CEHBT with an appropriate thickness of the AlxGa1−xAs graded layer offers the promise for analog, digital, and microwave device applications, especially for lower operation voltage and lower power consumption circuits.

Thermal reactions of Pd/AlxGa1−xAs contacts

Pd/AlxGa1−xAs Schottky contacts and their thermal reactions are studied by capacitance–voltage measurements, current–voltage measurements, and x-ray diffraction. The thickness of AlxGa1−xAs consumed by the Pd/AlxGa1−xAs reaction during annealing was calculated. For annealing temperatures below 300 °C the Schottky characteristics of the diodes were good but the electrical junction moves into AlxGa1−xAs after annealing. The amount of junction movement was calculated directly from our measurements. The diffusion coefficients of Pd in AlxGa1−xAs and the activation energy were estimated. The activation energy was found to be larger for higher Al concentration. PdAl, PdAs2, PdGa5, and Pd5Ga2 were detected in the compounds formed by the Pd/AlxGa1−xAs reaction after annealing.

AlxGa1−xAs LPE growth

AbstractAlxGa1−xAs LPE growth was studied within the temperature range of 930–900°C with Al concentrations in solutions from 0.04 to 2.4 at.%. AlAs concentration in layers has been shown to grow with the cooling rate increase of solution. Interface and volume nucleation parameter dependence of Ki and Kv and formation time tf on Al concentration in Ga solution have been found. Addition of Al to Ga solution increases critical values of As supersaturation (supercooling) and, as a result, increase in thickness of AlxGa1−xAs layers compared with GaAs layers have been determined in spite of As concentration lowering in Ga solution.