Changing PL Intensity from GaAs/Al0.3Ga0.7As Heterostructures due to the Chemisorption of SO2: Effects of Heterostructure Geometry

1993 ◽  
Vol 318 ◽  
Author(s):  
J.F. Geisz ◽  
T.F. Kuech ◽  
A.B. Ellis
Keyword(s):  
Chemical Sensor ◽  
Signal To Noise Ratio ◽  
Surface States ◽  
Surface Charges ◽  
Bulk Charge ◽  
Adsorption Of Gases ◽  
State Chemical ◽  
Pl Intensity ◽  
Measurable Change ◽  
Electronic Surface

ABSTRACTChemical adsorption of gases onto semiconductor surfaces results in a change in the density of electronic surface states. The corresponding change in the number of surface charges gives rise to a measurable change in the bulk charge distribution within the semiconductor. This phenomenon forms the basis of a novel solid-state chemical sensor device using the intensity of photoluminescence (PL) as a measurement technique. We have observed changes in the PL intensity from MOVPE-grown GaAs/Al0 3Ga0 7As heterostructures due to the chemisorption of SO2 onto “photowashed” GaAs surfaces. The photowashing technique is believed to reduce the density of preexisting surface states by removing As from the GaAs surface oxide. The PL signal-to-noise ratio and PL sensitivity characteristics of these chemical sensors may be dramatically improved by varying semiconductor structure. We have observed a range of PL enhancements upon exposure to 0.6% SO2 in flowing N2 from heterostructure layers with various thicknesses and doping densities. These results are explained by comparison with a FEM numerical model derived to correlate the relative PL intensity from various heterostructures to the surface charge density.

Electronic surface states in GaAs/Ga1 − xAlxAs superlattice: effect of surface location

Vacuum ◽  
1995 ◽  
Vol 46 (5-6) ◽  
pp. 459-463 ◽  
Author(s):  
M Stȩślicka ◽  
R Kucharczyk ◽  
EH El Boudouti ◽  
B Djafari-Rouhani ◽  
ML Bah ◽  
...  
Keyword(s):  
Surface States ◽  
Surface Location ◽  
Electronic Surface ◽  
Effect Of Surface

scholarly journals Covalent assembly of a two-dimensional molecular “sponge” on a Cu(111) surface: confined electronic surface states in open and closed pores

2014 ◽  
Vol 50 (57) ◽  
pp. 7628-7631 ◽  
Author(s):  
Aneliia Shchyrba ◽  
Susanne C. Martens ◽  
Christian Wäckerlin ◽  
Manfred Matena ◽  
Toni Ivas ◽  
...  
Keyword(s):  
Surface States ◽  
Two Dimensional ◽  
New Class ◽  
Trimesic Acid ◽  
Electronic Surface

We present a new class of on-surface covalent reactions, formed between diborylene-3,4,9,10-tetraaminoperylene and trimesic acid on Cu(111), which gives rise to a porous 2D-‘sponge’.

Novel Chemical Sensor Concept for Neutral Radical Detection in Gas Phase

2005 ◽  
Vol 876 ◽  
Author(s):  
Vladislav V. Styrov ◽  
Alex Y. Kabansky ◽  
Victor P. Grankin ◽  
Stanislav Kh. Shigalugov ◽  
Yuri I. Tyurin
Keyword(s):  
Gas Phase ◽  
Chemical Sensor ◽  
Proximate Analysis ◽  
Semiconductor Films ◽  
Neutral Radical ◽  
Enhanced Sensitivity ◽  
Radical Detection ◽  
State Chemical ◽  
Novel Concept ◽  
Heterogeneous Chemical Reactions

AbstractA novel concept of solid-state chemical sensors for neutral radical detection in gas-phase and related technique are proposed based on chemiluminescence of sensing materials excited by heterogeneous chemical reactions of radicals on sensor surface. The radical species of interest include H, O, N, O2, CO, SO, NO and others. Surface activated phosphors, nano-phosphors and semiconductor films are good candidates for sensors. The advantages of these sensors are the enhanced sensitivity (~105at/cm-3or better), real-time response, reliability, proximate analysis, ability to be fabricated in combination with up-to-date nanotechnologies.

scholarly journals Modeling of the Return Current in a Light-Addressable Potentiometric Sensor

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4566
Author(s):  
Tatsuo Yoshinobu ◽  
Daisuke Sato ◽  
Yuanyuan Guo ◽  
Carl Frederik Werner ◽  
Ko-ichiro Miyamoto
Keyword(s):  
Light Beam ◽  
Chemical Sensor ◽  
Series Resistance ◽  
Signal To Noise Ratio ◽  
Modulation Frequency ◽  
Specific Conductivity ◽  
Potentiometric Sensor ◽  
Capacitive Coupling ◽  
Return Current ◽  
Light Addressable Potentiometric Sensor

A light-addressable potentiometric sensor (LAPS) is a chemical sensor with a field-effect structure based on semiconductor. Its response to the analyte concentration is read out in the form of a photocurrent generated by illuminating the semiconductor with a modulated light beam. As stated in its name, a LAPS is capable of spatially resolved measurement using a scanning light beam. Recently, it has been pointed out that a part of the signal current is lost by the return current due to capacitive coupling between the solution and the semiconductor, which may seriously affect the sensor performance such as the signal-to-noise ratio, the spatial resolution, and the sensitivity. In this study, a circuit model for the return current is proposed to study its dependence on various parameters such as the diameter of contact area, the modulation frequency, the specific conductivity of the solution, and the series resistance of the circuit. It is suggested that minimization of the series resistance of the circuit is of utmost importance in order to avoid the influence of the return current. The results of calculation based on this model are compared with experimental results, and its applicability and limitation are discussed.

Electronic surface states in Ge

1972 ◽  
Vol 5 (12) ◽  
pp. L146-L150 ◽  
Author(s):  
M Elices ◽  
F Yndurain
Keyword(s):  
Surface States ◽  
Electronic Surface

Electronic surface states at steps in Si(111)2×1

1983 ◽  
Vol 132 (1-3) ◽  
pp. A338
Author(s):  
P. Chiaradia ◽  
G. Chiarotti ◽  
S. Selci ◽  
Zhu Zhi-Ji
Keyword(s):  
Surface States ◽  
Electronic Surface
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