Improved performance of GaSb-based MIR photodetectors through electrochemical passivation in sulphur containing solution
- PDF / 265,105 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 36 Downloads / 128 Views
B6.8.1
Improved performance of GaSb-based MIR photodetectors through electrochemical passivation in sulphur containing solutions A. Piotrowska1, E. Papis1, K. Golaszewska1, R. Lukasiewicz1, E. Kaminska1, T.T. Piotrowski1, R. Kruszka1, A. Kudla1, J. Rutkowski2, J. Szade3, A. Winiarski3, A. Wawro4, M. Aleszkiewicz4 1)
Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw, Poland Institute of Physics, Military Academy of Technology, 00-908 Warsaw, Poland 3) Institute of Physics, University of Silesia, 40-020 Katowice, Poland 4) Institute of Physics, PAS, Al. Lotnikow 32/46, 02-668 Warsaw, Poland 2)
ABSTRACT Sulfur passivation effects on the performance of LPE-grown GaSb/InGaAsSb/AlGaAsSb mesatype photodiodes operating in wavelengths range 1.9 – 2.3 µm have been investigated. (NH4)2S, Na2S, and (NH2)2CS have been chosen as sulfur sources in either aqueous or C3H7OH solutions. Electrochemical passivation of mesa side walls was proven to reduce photodiodes dark current and increasing their differential resistance by a factor of 4. As a result devices characterized by the detectivity of 1.5-2x1010 cmHz1/2/W and dark current density of 20 mA/cm2 at –0.5V bias have been fabricated and their long-term stability has been proven. INTRODUCTION GaSb-based semiconductor alloys are well recognized for their potential applications in MIR optoelectronics and thermophotovoltaics [1,2]. The implementation of these materials, however, has been hampered by an inability to reproducibly control their surface properties. GaSb is highly reactive and easily oxidizes under atmospheric conditions forming an oxide layer that is not self limiting, stable or abrupt. Moreover, during the oxidation process, a layer of elemental Sb may form at the oxide/GaSb interface giving rise to unwanted conduction paths parallel to the interface [3]. In search for appropriate passivating coatings the surface treatment in sulphur containing solutions has recently received much attention [4, 5]. In this work the formation of passivating coatings on GaSb, InGaAsSb (EG = 0.52 eV), and AlGaAsSb (EG = 1.25 eV) surfaces via electrochemical treatment in sulphur containing electrolytes has been investigated and the effect of sulphur passivation of mesa side walls on the electro-optical characteristics of GaSb/InGaAsSb/AlGaAsSb photodiodes operating in the 1.9 – 2.3 µm wavelengths range has been analyzed. The long-term stability of the surface passivation was of particular concern. EXPERIMENTAL DETAILS The GaSb samples used in these experiments were (100) oriented monocrystalline wafers doped with Te to the concentration of n=(1-5)x1017cm-3. The heterostructure materials and heterojunction photodiodes GaSb/n-In0.23Ga77As0.18Sb0.82/p-Al0.34Ga0.66As0.025Sb0.975 were grown by LPE. The composition of the liquid phase and the parameters of LPE growth were optimized to provide detectors operating up to 2.4 µm wavelengths range [6].
B6.8.2
Mesa photodiodes with 200 µm diameter active area were formed using photolithography and RIE in CCl4/H2 plasma [7]. AgTe/
Data Loading...
