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Mechanical Properties Optical Band Gaps And Hall Parameters As Thin Films At Varied Manganese Doping Levels

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dc.contributor.author Kemei, Solomon
dc.date.issued 2013-11
dc.date.accessioned 2022-12-15T07:42:22Z
dc.date.available 2022-12-15T07:42:22Z
dc.description.abstract Gallium Manganese Arsenide (Ga1-xMnxAs) is a p-type ferromagnetic material with high conduction charge carrier concentration compared to doped silicon and whose spin conductivity is dependent on temperature. The energy gap of the spin-based transistors increases with an increase in temperature. High temperature induces thermal stress which produces thermal strain in the forbidden region. Repeated and prolonged thermal stress at temperatures above the room temperature weakens the spin injector material. The weakening of the spin injector material by induced thermal stress develops creep failure at high temperature and at particular exposure time. The energy gap increases at high temperature and spin conductance is inhibited at fracture point of spin injector. The study determined storage modulus and loss modulus at temperature range of 45 °C ≤ T ≤ 70 °C for different Manganese Doping Levels (MDLs). It also determined the Young’s moduli, creep compliance and creep recovery at 30 °C and 40 °C for all MDLs using DMA 2980. Furthermore, it determined the optical absorbance and Hall effect parameters at 30 °C for all MDLs using OSA Spectro 320 and Van der Pauw experiments respectively. The samples were prepared using the RF Magnetron Sputtering Deposition Technique. The storage modulus of MDLs of 0 %, 1 % and 10 % decreased with increase in temperature while for 20% and 50 % it increased with increase in temperature. There was also a general reduction in loss moduli as temperature was increased at all MDLs suggesting a reduction in heat dissipation within the temperature range of 45 °C ≤ T ≤ 70 °C. The Hall mobility in the range 0 % ≤ MDLs ≤ 20 % was of order of 10-7 m2V-1s-1. For MDL of 50 %, Hall mobility was of order of 10-9 m2V-1s-1 and MDL of 10 % and 20 % was appropriate for use in making high speed data processing spintronic devices. The MDL of 1 % recorded a percentage creep recovery of 100 % at 30 °C and 95.42 % at 40 °C. MDL of 10 % recorded creep compliance of 9.8072 μm2/N at 40 °C and Young’s moduli of 2.4397×107 Pa and Initial Strain Jump of 8.1818×10-4 %. Lastly MDL of 20 % recorded the highest optical energy band gap of 0.69 eV compared to GaAs as a control sample that has optical band gap of 1.43 eV. The information obtained from DMA 2980 and Quantum Hall Effect experiments were compared and the variation of carrier concentration with environmental temperature determined. The results provided information for the spintronic device designers in terms of temperature, device size and application. en_US
dc.language.iso en en_US
dc.publisher Egerton University en_US
dc.subject Mechanical properties en_US
dc.title Mechanical Properties Optical Band Gaps And Hall Parameters As Thin Films At Varied Manganese Doping Levels en_US
dc.type Thesis en_US

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