Evidence of an oxygen recombination center in p+–n GaInNAs solar cells

Abstract

We have studied deep-level impurities in p+–n GaInNAs solar cells using deep-level transient spectroscopy (DLTS). These films were grown by atmospheric- and low-pressure metalorganic vapor-phase epitaxy. The base layer is doped with silicon, and the emitter layer is zinc doped. Two types of samples have been studied: samples were grown with and without the addition of oxygen impurity. Two electron traps were found in all samples. These are designated as: E1, at EC−0.23–EC−0.27 eV, E2 at EC−0.45 eV, and E2* at 0.77 eV. With the addition of oxygen impurity, DLTS showed additional traps designated as E3 (electron) at EC−0.59 eV and H3 (hole) at EV+0.59 eV. Using secondary ion mass spectroscopy, the oxygen concentration was found to be about 2–3×1019 and 1×1017 cm−3 in two sets of samples. However, only samples containing oxygen contained the two near-midgap levels (E3 and H3). We present evidence that these levels are associated with the oxygen defect. As we change the dc bias voltage, the E3 trap disappears in unison with the appearance of the H3 trap. Furthermore, E3 and H3 trap levels have comparable capture cross sections. This oxygen-related trap is an effective recombination center. The measured Shockley–Hall–Read lifetime for this center is about 0.6 μs.

Optical and electrical properties of modulation-doped n and p-type Ga x In1-x N y As1-y /GaAs quantum wells for 1.3 μm laser applications

“…Dilute nitrides has provided opportunities for a variety of optoelectronics device applications. Devices already demonstrated include diode lasers (Mitomo et al 2005), photodetectors (Heroux et al 1999), solar cells (Geisz and Friedman 2002), vertical cavity surface emitting laser (Calvez et al 2004a), vertical external-cavity surface emitting lasers (Calvez et al 2004b), semiconductor optical amplifiers (Calvez et al 2003) modulators (Balcioglu Aahrenkiel and Friedman 2000) and heterojuction bipolar transistors (HBTs) (Li et al 2000). A wide range of novel devices could still benefit from dilute nitrides; commercially, the most important devices are for inexpensive optical fiber data transmission at 1,300 nm for metro-area links over 10 to 20 km.…”

Temperature-dependent optical properties of single quantum well with high nitrogen content for application grown by molecular beam epitaxy

“…In fact, InGaNAs-based vertical cavity surface-emitting laser (VCSEL), Vertical-cavity semiconductor optical amplifier (VCSOA), edge-emitting laser, photodetector, light emitting diode (LED), solar cell, modulators and heterojunction bipolar transistors (HBTs) have already been demonstrated [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Commercially, extensive groups focus their researches on pushing the emission wavelength of the dilute nitride above 1:3 mm, potentially useful for long haul links [25][26][27][28][29].…”

Trap-dominated minority-carrier recombination in GaInNAs pn junctions

“…Over the 0.9-1.1 eV range of band gaps and for both p/n and n/ p junctions, the various junctions all show E t ϪE VBM ϭ0.47Ϯ0.05 eV or E CBM ϪE t ϭ0.42Ϯ0.05 eV; thus, the trap level is probably of the same physical origin in all the junctions. To determine which of these two possibilities for E t is the operative one, we note that Balcioglu et al 15 used DLTS to study a set of GaInNAs pn junctions comparable in structure and growth to the ones we discuss here. In all their samples they found traps they designated E1 at E CBM Ϫ0.25 eV; E2 at E CBM Ϫ0.45 eV; and E2* at E CBM Ϫ0.77 eV.…”