CC BY
17LD-I-10
Low noise GaInAsSb/GaAlAsSb Avalanche Photodiodes for Detecting Radiation of Solid-State Lasers
M.P. Mikhailova, A.P. Dmitriev, I.A. Andreev, E.V. Kunitsyna, E.V. Ivanov, Yu.P. Yakovlev
Ioffe Institute, 26 Politekhnicheskaya str., 194021 St. Petersburg, Russia kunits@iropt9. ioffe.ru
Avalanche photodiodes for the detection of high-frequency laser radiation should meet a number of requirements including high avalanche gain, large ratio of the impact ionization coefficients for holes and electrons, fast response time and low excess noise factor.
The GaSb band structure combines two unique features: firstly, the heavy L-valley in the conduction band for the (111) direction that is situated 85 meV below T-minimum so as the considerable number of electrons are in the T-valley and besides, the band "resonance", i.e. Eg « Ao , where Ao is the spinorbit splitting of the valence band. It is shown theoretically and experimentally [1] that in GaSb-related materials the maximum ratio of impact ionization coefficients for holes P and electrons a can be achieved due to monopolarity of multiplication by holes from the spin-orbit split off valence band, the threshold energy value for which is minimal and equal to em « Ao. This study has allowed us to suggest a new approach to developing the almost "noiseless" avalanche photodiodes. The avalanche photodiodes with separate absorption and multiplication regions (SAM APD) have been developed based on GaInAsSb/GaAl(As)Sb heterostructures grown on the GaSb (111) substrates. The minimum detectable power level ^<Papd> for the optoelectronic receiver using SAM APD was determined under illumination by monochromatic radiation with wavelength of X=2.1 ^m and calculated [2] at the ratio of the ionization coefficients of k = p/a « 60 and the multiplication factor of M = 30-40. It was accepted in our calculations, that the bit rate is B = 500 Mbit/s, the bit error rate is BER=10-9, the diameter of the APD sensitive area is 200 ^m, and the value of the sensitivity at the maximum of the spectral characteristic (X = 2.1 ^m) is 1.1 A/W. The minimum excess noise factor F(M) = 1.6 was reached at k = p/a » 60 and M = 20-40.
The optoelectronic receiver with the GaInAsSb/GaAl(As)Sb SAM APD was tested under illumination of the YLF:Ho (X=2.06 ^m) and YAG-Cr,Tm:Ho (X=2.09 ^m) solid-state lasers. A comparison of the minimum detectable power level for the GaInAsSb/GaAl(As)Sb SAM APD at X=2.1 ^m and for the Ge APD at X =1.55 ^m was made. The SAM APD receiver demonstrate ^<Papd>= - 42.3 dBm at M=34-39, as well as the threshold value of the pulse energy of 6.2x10-16 J. The receiver with the standard Ge APD has ^<Papd>= - 41.8 dBm at M=10 (p/a=2) and the minimum detectable pulse energy of 6.2x10-15 J.
These results show the potential for use of the GaInAsSb/GaAl(As)Sb SAM APDs in the systems for optical fiber communication including the detection of weak pulse signals of solid-state lasers in IR region of 2-3 ^m.
[1] M.P. Mikhailova and I.A. Andreev, Mid-infrared Semiconductor Optoelectronics, ed. by A. Krier (Springer-Verlag), Part III, 547 (2006).
[2] R.C. Smith and S.D. Personick, Semiconductor Devices for Optical Communications, ed. by H. Kressel (Springer-Verlag), Chapter 4, 89 (1982).
