InP-based short-wave infrared and midwave infrared photodiodes using a novel type-II strain-compensated quantum well absorption region

Recent Advances in High Speed Photodetectors for eSWIR/MWIR/LWIR Applications

High speed photodetectors operating at a telecommunication band (from 1260 to 1625 nm) have been well studied with the development of an optical fiber communication system. Recent innovations of photonic systems have raised new requirements on the bandwidth of photodetectors with cutoff wavelengths from extended short wavelength infrared (eSWIR) to long wavelength infrared (LWIR). However, the frequency response performance of photodetectors in these longer wavelength bands is less studied, and the performances of the current high-speed photodetectors in these bands are still not comparable with those in the telecommunication band. In this paper, technical routes to achieve high response speed performance of photodetectors in the extended short wavelength infrared/mid wavelength infrared/long wavelength infrared (eSWIR/MWIR/LWIR) band are discussed, and the state-of-the-art performances are reviewed.

InAs/InAsSb Type-II Strained-Layer Superlattice Infrared Photodetectors

The InAs/InAsSb (Gallium-free) type-II strained-layer superlattice (T2SLS) has emerged in the last decade as a viable infrared detector material with a continuously adjustable band gap capable of accommodating detector cutoff wavelengths ranging from 4 to 15 µm and beyond. When coupled with the unipolar barrier infrared detector architecture, the InAs/InAsSb T2SLS mid-wavelength infrared (MWIR) focal plane array (FPA) has demonstrated a significantly higher operating temperature than InSb FPA, a major incumbent technology. In this brief review paper, we describe the emergence of the InAs/InAsSb T2SLS infrared photodetector technology, point out its advantages and disadvantages, and survey its recent development.

Dynamic model and bandwidth characterization of InGaAs/GaAsSb type-II quantum wells PIN photodiodes

In this work, we demonstrated a normal incident PIN InGaAs/GaAsSb type-II multiple quantum wells (MQW) photodiode on InP substrate for 2 μm wavelength high-speed operation. The photodiode has a responsivity of 0.35 A/W at room temperature at 2 μm, and a 3 dB bandwidth of 3.7 GHz. A carrier dynamic model is developed to study the bandwidth of the multiple quantum wells photodiode. Simulation results match the experimental data well, and analysis shows that hole transport limits the 3 dB bandwidth performance. By optimizing the MQW design, higher bandwidth performance (>10 GHz) can be achieved.

Investigation of deep level defects on Beryllium compensation doping of In0.53Ga0.47As/GaAs0.49Sb0.51 type-II superlattice photodiodes

In this paper, deep level transient spectroscopy (DLTS) characterization was performed on Beryllium compensation doping of InGaAs/GaAsSb type-II superlattice photodiode. Three electron traps with the energy levels located at E_c-0.11 eV (E1), E_c-0.28 eV (E2), E_c-0.17 eV (E3), and a hole trap situated at E_v + 0.25 eV (H1) were revealed. The position distribution and depth concentration of these traps in SL absorption region was also explored. Furthermore, the bandlike states (E2) and localized states (E1 and H1) of extended defects were confirmed by DLTS measurements as a function of the filling-pulse time, these traps as generation-recombination centers are responsible for dominant dark current.

2 μm wavelength range InP-based type-II quantum well photodiodes heterogeneously integrated on silicon photonic integrated circuits

The heterogeneous integration of InP-based type-II quantum well photodiodes on silicon photonic integrated circuits for the 2 µm wavelength range is presented. A responsivity of 1.2 A/W at a wavelength of 2.32 µm and 0.6 A/W at 2.4 µm wavelength is demonstrated. The photodiodes have a dark current of 12 nA at -0.5 V at room temperature. The absorbing active region of the integrated photodiodes consists of six periods of a "W"-shaped quantum well, also allowing for laser integration on the same platform.

Effect of Cs adsorption on the photoemission performance of GaAlAs photocathode

The effect of Cs adsorption on the photoemission performance of a reflection-mode GaAlAs photocathode in an ultrahigh vacuum chamber has been investigated. The experiments for Cs/O activation, multiple recaesiation, and degradation are performed on a GaAlAs photocathode. Meanwhile, the Cs/O activated and recaesiated photocurrent curves, degraded photocurrent curves, and spectral response curves are measured and analyzed. Besides, the performance parameters of the photocathodes are obtained by using the formula to fit with the experimental quantum efficiency curves. The results show that the Cs atoms not only make the atomically clean surface form the negative electron affinity, but also make the degraded photocathode recover to a good level. The quantum efficiency and the lifetime of GaAlAs photocathode become lower with increasing the recaesiation times.