Characterization of midwave infrared InAs/GaSb superlattice photodiode

Abstract

We report on structural, electrical, and optical characterizations of midwave infrared InAs/GaSb superlattice (SL) p-i-n photodiodes. High-quality SL samples, with 1 μm thick active region (220 SL periods), exhibited a cut-off wavelength of 4.9 μm at 80 K. Using a capacitance-voltage measurement technique performed on mesa diode, the residual background concentration in the nonintentionally doped region was determined to be 3×1015 cm−3 at 80 K. Extracted from current-voltage characteristics, R0A products above 4×105 Ω cm2 at 80 K were measured, and the quantitative analysis of the J-V curves showed that the dark current density of SL photodiode is dominated by generation-recombination processes. Front-side illuminated photodiodes produced responsivity at 80 K equal to 360 mA/W at 4.5 μm.

Passivation of type II InAs/GaSb superlattice photodetectors with atomic layer deposited Al<sub>2</sub>O<sub>3</sub>

“…A comparison of our results with recent data [9,[16][17][18][19][20], shows that ALD grown Al 2 O 3 passivated T2SL photodetectors are very promising. Oxide layers of few nanometers thick native oxide layers form very quickly on freshly etched surface of the superlattice since they are very reactive [21]. Oxygen reacts with surface metals to form oxides like; Sb 2 O 3 , Ga 2 O 3 , In 2 O 3 and As 2 O 3 .…”

Electrical performance of InAs/AlSb/GaSb superlattice photodetectors

“…TAT current component, which is about four orders of magnitude lower than GR current, has negligible influence on our calculations. The TAT current can be stated as [11,14]: where m * e is the tunnelling electron effective mass, M is the matrix element associated with the trap potential assumed to be 10 À23 eV 2 cm 3 , N t is the trap density equal to 2 Â 10 11 cm À3 , Z is Planck's constant, E is the electric field strength across the depletion region. Table 1 shows some detector parameters for calculations of dark current density.…”

“…In the lower temperature range (100e80 K), the dominant mechanism starts to become generation recombination (GR) which mostly depends on the deep trap levels inside the band gap (Eg/2). To illustrate the bias dependent dominant dark current components of diffusion (J DIFF ) and GR (J GR ) current, we use the model given elsewhere [14]. We then fit the dark current densities to determine the minority carriers of diffusion and GR lifetimes.…”

Temperature dependence performances of InAs/GaSb superlattice photodiode

“…Type-II InAs/GaSb superlattices (SL) photodiode is under development as a possible alternative technology for high performance infrared (IR) imaging systems [1] in the Mid-Wave IR (MWIR 3-5 lm) spectral windows [2][3][4][5][6][7][8], competing with the currently dominant MWIR detector technologies based on HgCdTe and InSb materials. However, to enhance the device performances, a better knowledge of electrical properties [9], carrier-lifetime [10], residual background carriers [11], and noise measurements of SL photodiode [12] are still necessary in the MWIR domain.…”

“…Dark current measurement is an efficient way to verify the quality of an infrared photodetector and many works have already been reported in the literature concerning MWIR InAs/GaSb SL photodiodes [2][3][4][5][6][7][8][13][14][15]. Low dark current density (J dark ) values are needed in order to achieve high performance focal plane arrays (FPAs) with low noise equivalent temperature difference (NETD), but the identification of each individual current mechanism, such as diffusion, generation-recombination (GR), band-to-band tunneling (BTB) and trap-assisted tunneling (TAT) currents, is very important for the understanding of the pin photodiode and then to improve SL device performances.…”