Blue–green to near-IR switching electroluminescence from Si-rich silicon oxide/nitride bilayer structures

Abstract

Blue-green to near-IR switching electroluminescence (EL) has been achieved in a metal-oxide-semiconductor light emitting device, where the dielectric has been replaced by a Si-rich silicon oxide/nitride bilayer structure. To form Si nanostructures, the layers were implanted with Si ions at high energy, resulting in a Si excess of 19%, and subsequently annealed at 1000°C. Transmission electron microscopy and EL studies allowed ascribing the blue-green emission to the Si nitride related defects and the near-IR band with the emission of the Si-nanoclusters embedded into the SiO 2 layer. Charge transport analysis is reported and allows for identifying the origin of this twowavelength switching effect. © 2011 Optical Society of America OCIS codes: 250.0250, 230.2090, 230.6080, 260.3800.Silicon-rich silicon oxide (SRSO) and silicon-rich silicon nitride (SRSN) have drawn great interest in the last decades as active dielectric matrices in optoelectronic devices [1][2][3][4]. Particularly, these materials have been used in the fabrication of low-cost light emitting devices compatible with the mainstream Si technology, They also provide a solution to the monolithic integration of electronic and optical technologies on the same Si chip. Different electroluminescence (EL) excitation mechanisms have been reported, such as hot electrons [5] and optically active defects [6] or field-effect EL using pulsed excitation [1]. The EL emission of the Si-nanocrystals (Si-ncs) embedded in SiO 2 is usually in the red-IR and shows a narrow shift capability depending on Si-nc size [1,3]. Regarding Si nitrides, luminescence in the bluegreen is also reported, ascribed either to Si nitride related defects or Si-ncs [4,7]. In addition, some strategies have been employed in order to extend the EL emission to different spectral region. For instance, defects created by dopants such as rare-earth ions can lead to light emission from UV to near-IR, depending on their specific energy level structure [8].In this Letter we report two-wavelength switching metal-nitride-oxide-semiconductor light emitting devices (MNOSLED) based on a SRSO/SRSN bilayer structure.The devices are similar to metal-oxide-semiconductor field-effect transistors with a 100 nm thick polycrystalline silicon layer used as an optically transparent gate electrode. Since its transmittance spectrum peaks at 470 nm and 760 nm [3], the final EL spectra of the devices are modulated accordingly. In order to combine light emission from different matrices, a SRSO/SRSN bilayer structure was designed ad hoc to form the insulator of the transistor. The Si excess in the SiO 2 and Si 3 N 4 layers was introduced by ion implantation. A subsequent annealing treatment at 1000°C during one hour was performed to recover the matrices and precipitate the Si-ncs. The implantation parameters (energy and dose) were chosen by stopping and range of ions in matter simulations to obtain a Si excess of 19%, attending to photoluminescence studies in previous works [7]. Energy filtered transmission electron micr...

Correlation between charge transport and electroluminescence properties of Si-rich oxide/nitride/oxide-based light emitting capacitors

“…9 or in Ref. 10 for the ONO-based devices to firmly confirm the proposed assertions. To gain more in-depth into the physics of these mechanisms, in this paper we present a detailed study of the charge transport and electroluminescent mechanisms as a function of temperature.…”

“…This feature is because of the low supply of minority carriers by the inverted substrate (electrons). It has to be also mentioned that such a depletion effect (and thus rectifying behavior) did not occur in the MNOSLED transistor structures 10 since the minority carriers can be supplied from the highly doped source and drain regions of the transistor. In the accumulation regime, a good conductivity at low and high voltages is observed.…”

“…[1][2][3][4][5][6][7][8][9][10] Silicon-rich silicon nitride (SRSN) and silicon-rich silicon oxide (SRSO) materials have mostly been considered due to their good emission properties (under optical and electrical excitation) and compatibility with the mainstream complementary metal oxide semiconductor (CMOS) technology. [1][2][3][4][5][6][7][8] Much effort has been dedicated to improve the electroluminescence (EL) intensity as well as the efficiency of the light-emitting devices.…”

“…[1][2][3][4] Published works span from those centering the attention on the material optimization in terms of the different fabrication processes, 6,7 to those that mostly focus on the electrical and EL properties. [8][9][10] Efficient light-emitting devices have already been demonstrated using either SRSN or SRSO films. 2,4 In former papers, we have reported the development of metal-nitride-oxide-semiconductor light-emitting devices that we called MNOSLEDs.…”

“…2,4 In former papers, we have reported the development of metal-nitride-oxide-semiconductor light-emitting devices that we called MNOSLEDs. 9,10 A typical structure of metaloxide-semiconductor field effect transistor (MOSFET), where the gate oxide was substituted by an oxide/nitride (ON, bi-layer) or oxide/nitride/oxide (ONO, tri-layer) gate stack was used. The photometric analysis conducted in these layers represented a proof of concept for the development of silicon-based solid state lighting.…”