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Results for “semiconductor thin films”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Plasma Processing of Metallic and Semiconductor Thin Films in the Fisk Plasma Source

The use of plasmas to process materials has become widespread throughout the semiconductor industry. Plasmas are used to modify the morphology and chemistry of surfaces. We report on initial plasma processing experiments using the Fisk Plasma Source. Metallic and semiconductor thin films deposited on a silicon substrate have been exposed to argon plasmas. Results of microscopy and chemical analyses of processed materials are presented.

Lampkin, Gregory↗
NASA NTRS1997

Computer Controlled Magnetotransport Setup for the Characterization of Semiconductor Thin Films

We have considered a computer controlled magnetotransport setup using LabWindows environment. It allows for measurements of resistivity, Hall resistance, carrier concentration and charge mobility in semiconductor thin films using a van der Pauw configuration. The setup features an electromagnet (B = 0.7 Tesla) a 80486-DX 33 computer with a National Instrument AT-MIO 16 AD/DA and a GPIB interface board. A Keithely 224 current source and a Keithley 196 digital voltmeter were also used in the setup. Plans for the addition of capabilities to allow for magnetic field sweeping and the performance of measurements as a function of temperature will be presented.

Ducoudray, G. O.↗
NASA NTRS1966

Thin-film semiconductor rectifier has improved properties

Cadmium selenide-zinc selenide film is used as a thin film semiconductor rectifier. The film is vapor-deposited in a controlled concentration gradient into a glass substrate to form the required junctions between vapor-deposited gold electrodes.

Source record↗
DOE OSTI2023

Highly stretchable polymer semiconductor thin films with multi-modal energy dissipation and high relative stretchability

Abstract Stretchable polymer semiconductors (PSCs) have seen great advancements alongside the development of soft electronics. But it remains a challenge to simultaneously achieve high charge carrier mobility and stretchability. Herein, we report the finding that stretchable PSC thin films (<100-nm-thick) with high stretchability tend to exhibit multi-modal energy dissipation mechanisms and have a large relative stretchability ( rS ) defined by the ratio of the entropic energy dissipation to the enthalpic energy dissipation under strain. They effectively recovered the original molecular ordering, as well as electrical performance, after strain was released. The highest rS value with a model polymer (P4) exhibited an average charge carrier mobility of 0.2 cm 2 V −1 s −1 under 100% biaxial strain, while PSCs with low rS values showed irreversible morphology changes and rapid degradation of electrical performance under strain. These results suggest rS can be used as a parameter to compare the reliability and reversibility of stretchable PSC thin films.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Low-temperature processed beta-phase In 2 Se 3 ferroelectric semiconductor thin film transistors

As scaling becomes increasingly difficult, there is growing interest in vertical or three-dimensional stacking of transistors and especially memory. Ferroelectric semiconductor field effect transistors can be key enablers to improve energy efficiency and overall chip and memory performance. In this work, low-temperature processed, back-end-of-the-line compatible transistors were demonstrated by depositing a layered chalcogenide ferroelectric semiconductor, beta-phase In 2 Se 3 , at temperature as low as 400 °C. Top gate n-channel In 2 Se 3 thin film transistors were fabricated with field-effect mobility ∼1 cm 2 V −1 s −1 , and simple polarization switching based memory results are presented.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Dynamic processes in transient phases during self-assembly of organic semiconductor thin films

Understanding and manipulating crystallization processes has been an important challenge for solution-processed organic thin films, both for fundamental studies and for fabricating thin films with near-intrinsic charge transport properties. We report an in situ X-ray scattering study of the crystallization of 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C 10 ) during its deposition from solution. At temperatures modestly below the smectic-E/crystalline phase boundary, the crystallization goes through a transient liquid crystal state before reaching the final stable crystalline phase. Significant dynamics occur in the first few seconds of the transition, which are observed through fluctuations in the X-ray scattering intensity, and are correlated with the time interval that the transient thin film coexists with the evaporating solvent. The transition to the stable crystalline phase takes minutes or even hours under these conditions, which may be a result of the asymmetry of the molecule. Transient phases are of potential interest for applications, since they can act as a route to self-assembly of organic thin films. However, our observations show that the long-lived monolayer-stacked intermediate state does not act as a template for the bilayer-stacked crystalline phase. Rather, the grain structure is replaced through nucleation, where the nucleation free-energy barrier is related to a potential barrier that prevents molecules to flip their long axis by 180°.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Study of Indium Chloride Vapor Treatment on Cu(In,Ga)Se 2 Semiconductor Thin Films

The recrystallization by indium chloride of Cu(In,Ga)Se 2 thin films deposited by co-evaporation at 350°C was studied. The process of recrystallization consists of the postdeposition treatment of CIGS sample by InCI3 vapor for 30 minutes with emphasis on grain growth. Here, the treatment resulted in uniform increased grain size and improved crystallinity. XRD measurements suggests the formation of indium rich phase. Dynamic SIMS were also performed to further understand the process, phase separation and the extent of gallium depletion.

14 SOLAR ENERGY↗
DOE OSTI2021

Studying the Recrystallization of Cu(InGa)Se 2 Semiconductor Thin Films by Silver Bromide In-situ Treatment

Cu(In,Ga)Se 2 samples were fabricated using a 3-stage thermal co-evaporation process on molybdenum back contact at low temperature. The process of recrystallization was carried out in between the 2 nd and 3 rd stages by flashing 25 mg of AgBr for 2 minutes. A change in morphological structure was observed as small grains transformed into large grains, as confirmed by XRD and SEM measurements. The decrease of the Ga gradient, seen in the SIMS depth profile, suggests Ga interdiffusion due to AgBr treatment. Altogether, the AgBr treatment contributes to a general improvement in device performance as compared to the as-deposited devices.

14 SOLAR ENERGY↗
NASA NTRS1992

Use of space ultra-vacuum for high quality semiconductor thin film growth

The utilization of space for materials processing is being expanded through a unique concept of epitaxial thin film growth in the ultra-vacuum of low earth orbit (LEO). This condition can be created in the wake of an orbiting space vehicle; and assuming that the vehicle itself does not pertub the environment, vacuum levels of better than 10 exp -14 torr can be attained. This vacuum environment has the capacity of greatly enhancing epitaxial thin film growth and will be the focus of experiments conducted aboard the Wake Shield Facility (WSF) currently being developed by the Space Vacuum Epitaxy Center (SVEC), Industry, and NASA.

Ignatiev, A.↗
DOE OSTI2021

Vapor Treatment and In-situ Recrystallization by Copper Chloride on Cu(In,Ga)Se 2 Thin Film

Deposition of CIGS semiconductor thin films was performed at low temperature and high rate by three-stage coevaporation process on molybdenum coated glass substrate. Here, a vapor treatment was done in between the second and third stage by flashing CuCl 2 for 5 mins at 400 °C. A large change in morphology and crystal structure was observed after the treatment. XRD and SEM showed that small grains transformed into large grains. A smoother Ga profile was observed by SIMS measurements for the treated films as compared to as-deposited films. Furthermore, the Na profile was also modified in the recrystallized samples, with a lower content after recrystallization.

14 SOLAR ENERGY↗
DOE OSTI2022

Impact of Indium Chloride Treatment on the Properties of CuInSe 2 Thin Films

Copper Indium diselenide (CIS) semiconductor thin films were deposited by single-stage process. Following the deposition, annealing and recrystallization of CIS was carried out in the presence of InCl 3 at different temperatures. Increase in grain size was observed by SEM in all cases. Increase in peak intensity was observed by XRD after treatment, correlating well with the SEM results. Measurements of the composition by both XRF and EDS indicate significant changes, notably a decrease in copper content. Here, this will likely be an issue for device performance and will need to be addressed.

14 SOLAR ENERGY↗
NASA NTRS1976

Outline and comparison of the possible effects present in a metal-thin-film-insulator-semiconductor solar cell

The advantages possible with the insertion of a thin-film insulating or semi-insulating layer between a metal and a semiconductor to form the MIS photovoltaic device have been presented previously in the literature. This MIS configuration may be considered as a specific example of a more general class of photovoltaic devices: electrode-thin-film-insulator-semiconductor devices. Since the advantages of the configuration were pointed out, there has been considerable experimental interest in these photovoltaic devices. Because the previous analysis showed that the introduction of the insulator layer could produce several different but advantageous effects, this paper presents a further outline giving a comparison of these effects together with their ramifications.

Fonash, S. J.↗